microB.txt

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microB.txt
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MicroB questions
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  1. The class of antibiotics known as the quinolones is bactericidal. Which of the following is the best characterization of their mode of action on growing bacteria?
    • a. Inactivation of penicillin-binding protein II
    • b. Inhibition of beta -lactamase
    • c. Inhibition of DNA gyrase
    • d. Inhibition of reverse transcriptase
    • e. Prevention of the cross-linking of glycine
  2. Vancomycin-indeterminate S. aureus (VISA) has recently been reported in the United States. Which of the following statements concerning VISA is correct?
    • a. Patients with VISA isolates need not be isolated
    • b. Minimum inhibitory concentration (MIC) for vancomycin is at least 1.0 mcg/mL
    • c. VISAs have emerged because of the extended use of vancomycin for methicillin-resistant S. aureus (MRSAs)
    • d. VISA isolates are infrequent, so surveillance at the present time is not warranted
    • e. VISA isolates are usually methicillin susceptible
  3. A 55-year-old male develops malaise, fever up to 103.5°C, non-productive cough, headache, and shortness of breath, a few days after he repaired the cooling system of an old hotel. A chest x-ray reveals fluid in his lungs. From a sputum sample, a gram-negative rod grew slowly on a buffered cysteine containing charcoal-yeast agar. Which of the following antibiotic therapies is most appropriate for treating this patient?
    • a. Ampicillin
    • b. Ceftriaxone
    • c. Erythromycin
    • d. Penicillin
    • e. Vancomycin
  4. A 60-year-old male resident from a nursing home presents to the emergency room with a fever of 41°C, shaking chills, severe pain to the right side of his chest that worsens with breathing, and a productive cough with blood-tinged sputum. During the previous 3 days, he noted cold-like symptoms. Gram stain evaluation of the sputum reveals gram-positive diplococcic that grow into a-hemolytic colonies on blood agar. Which of the following antibiotic therapies is the most appropiate treatment for this patient?
    • a. Ampicillin
    • b. Ceftriaxone
    • c. Erythromycin
    • d. Penicillin
    • e. Vancomycin
  5. A 12-year-old boy, after a camping trip near a wooded area in Northern California, is taken to the emergency room after complaining of a headache. He has an erythema migrans rash around what appears to be a tick bite.Which of the following is the antibiotic of choice for treating this patient?
    • a. Ampicillin
    • b. Ceftriaxone
    • c. Erythromycin
    • d. Penicillin
    • e. Vancomycin
  6. A 6-year-old girl presents to her pediatrician with fever, headache and a sore throat. She has swollen tender cervical lymph nodes, and her oropharynx is red with a gray-white exudate covering both her tonsils.A rapid strep test of her throat swab is positive, and the culture subsequently shows beta hemolytic Streptococcus. Which of the following antibiotic therapies is most appropiate for treating this patient?
    • a. Ampicillin
    • b. Ceftriaxone
    • c. Erythromycin
    • d. Penicillin
    • e. Vancomycin
  7. A young woman being treated with a broad-spectrum antimicrobial develops endoscopically observed microabscesses and diarrhea. Which of the following is the therapy of choice for this form of enterocolitis?
    • a. Ampicillin
    • b. Ceftriaxone
    • c. Erythromycin
    • d. Penicillin
    • e. Vancomycin
  8. Antibiotic therapy may be a critical step in the management of patients infected with the following microorganisms. Which organism listed below would not benefit from prompt antibiotic treatment?
    • a. anthracis
    • b. botulinum

    • c. difficile
    • d. perfringens
    • e. tetani
  9. A 75-year-old African American male with neurogenic bladder presents to the emergency room with hypertension, fever up to 104.6°F, and nausea and vomiting. The urine from his foley catheter gives a positive culture for Enterococcusfaecalis. Which of the following antibiotics inhibits the final peptide bond between d-alanine and glycine and is the most appropriate treatment for this patient?
    • a. Amdinocillin
    • b. Amphotericin
    • c. Chloramphenicol
    • d. Penicillin
    • e. Trimethoprim
  10. A patient with leukemia has a chest CT finding that suggests aspergillosis. Which of the following antimicrobial binds sterols and alters membrane permeability, and would most likely be used in this patient’s treatment?
    • a. Amdinocillin
    • b. Amphotericin
    • c. Chloramphenicol
    • d. Penicillin
    • e. Trimethoprim
  11. A 10-week-old infant is diagnosed with meningitis. A lumbar puncture reveals numerous neutrophils and gram-positive rods. She is admitted to the hospital and is thought to be allergic to beta-lactams. Which of the following antibiotics attaches to 505 ribosome, inhibits peptidyl transferase, and would most likely be used to treat this patient?
    • a. Amdinocillin
    • b. Amphotericin
    • c. Chloramphenicol
    • d. Penicillin
    • e. Trimethoprim
  12. A patient presents to the emergency room with vomiting, diarrhea, high fever, and delirium. Upon physical exam, you notice large, painful buboes, and disseminated intravascular coagulation. Laboratory diagnosis of aspirate taken from the bubo reveals a gram-negative rod with bipolar staining resembling a safety pin. Which of the following antibiotics is most appropiate as part of your immediate treatment?
    • a. Ceftazidine
    • b. Ceftriaxone
    • c. Penicillin
    • d. Streptomycin
    • e. Vancomycin
  13. A 3-year-old girl who has missed several scheduled immunizations presents to the emergency room with a high fever. She is irritable and has a stiff neck. Fluid from a spinal tap reveals 20,000 white blood cells per milliliter with 85% polymorphonuclear cells. Which of the following is the preferred third-generation cephalosporin with good activity against organisms of childhood meningitis?
    • a. Ceftazidine
    • b. Ceftriaxone
    • c. Penicillin
    • d. Streptomycin
    • e. Vancomycin
  14. A 28-year-old female just returned from a 1-week cruise with stops along the coast of Mexico. Forty-eight hours after her return she is reported to have headache, fever, abdominal cramps, and constipation. Over the next 5 days her fever increases with continued complaints of myalgias, malaise, and anorexia. A blood culture is positive for S. typhi. Her condition improves with a treatment course of a cephalosporin. Which of the following is the function of porins that would prevent the effective use of other antimicrobials ?
    • a. Hydrolysis of hydrophilic antimicrobials
    • b. Metabolism of phosphorylated intermediates
    • c. Serologic stabilization of the O antigen
    • d. Inactivation of hydrophobic antimicrobials
    • e. Transfer of small molecules through the outer membrane
  15. A patient presents to the emergency room with a progressive fever, cough, and general malaise. History determines that he works with sheep on a farm and had just been involved in wool harvesting. Which of the following antibiotics is most appropriate as part of your immediate treatment?
    • a. Ceftazidine
    • b. Ceftriaxone
    • c. Penicillin
    • d. Streptomycin
    • e. Vancomycin
  16. During the course of his hospital stay, a severely burned 60-year-old male develops a rapidly disseminating bacterial infection. Small gram-negative rods that are oxidase positive are cultured from green pus taken from the burn tissue. Which of the following third-generation cephalosporin will most likely have the best primary activity against this etiologic agent?
    • a. Ceftazidine
    • b. Ceftriaxone
    • c. Penicillin
    • d. Streptomycin
    • e. Vancomycin
  17. Laboratory results of a clinical specimen from a patient with hospital-acquired pneumonia reveal the presence of Staphylococcus aureus with a methicillin-resistant plasmid. Which of the following drugs is the best immediate treatment?
    • a. Ceftazidine
    • b. Ceftriaxone
    • c. Penicillin
    • d. Streptomycin
    • e. Vancomycin
  18. Antibiotics that inhibit dihydrofolic acid reductase in bacteria up to 50,000 times more than in mammalian cells is represented by which of the following agents?
    • a. Amdmocillin
    • b. Amphotericin
    • c. Chloramphenicol
    • d. Penicillin
    • e. Trimethoprim
  19. An 18-year-old college freshman presents with fever of 103°F, headache, right flank pain, nausea and vomiting, and urinary frequency with hematuria and dysuria. Renal ultrasound demonstrates a right urinary stone with right hydronephrosis. Which of the following antibiotics binds to PBP-2 and is the most appropriate treatment option?
    • a. Amdinocillin
    • b. Amphotericin
    • c. Chloramphenicol
    • d. Penicillin
    • e. Trimethoprim
  20. A patient presents to the emergency room with vomiting, diarrhea, high fever, and delirium. Upon physical exam, you notice large, painful buboes, and disseminated intravascular coagulation. Laboratory diagnosis of aspirate taken from the bubo reveals a gram-negative rod with bipolar staining resembling a safety pin. Which of the following antibiotics is most appropriate as part of your immediate treatment?
    • a. Ceftazidine
    • b. Ceftriaxone
    • c. Penicillin
    • d. Streptomycin
    • e. Vancomycin
  21. Regarding antimicrobial drugs that act by inhibiting nucleic acid synthesis in bacteria, which one of the following is the MOST accurate?
    • a. Quinolones, such as ciprofloxacin, inhibit the RNA poly-merase in bacteria by acting as nucleic acid analogues
    • b. Rifampin inhibits the RNA polymerase in bacteria by binding to the enzyme and inhibiting messenger RNA synthesis
    • c. Sulfonamides inhibit the DNA polymerase in bacteria by causing chain termination of the elongating strand
    • d. Trimethoprim inhibits the DNA polymerase in bacteria by preventing the unwinding of double-stranded DNA
  22. Endotoxin is an important underlying cause of septic shock and death, especially in hospitalized patients. Regarding endotoxin, which one of the following is the MOST accurate?
    • a. It acts by phosphorylating the G stimulating protein
    • b. It is a polypeptide with an A-B subunit configuration
    • c. It induces the synthesis of tumor necrosis factor
    • d. It is found primarily in gram-positive rods
    • e. It can be treated with formaldehyde to form an effective toxoid vaccine
  23. A family routinely consumed unpasteurized milk, claiming "better taste." Several members experienced a sudden onset of crampy abdominal pain, fever, and bloody, profuse diarrhea. C. jejuni was isolated and identified from all patients. Which of the following is the treatment of choice for this type of enterocolitis?
    • a. Ampicillin
    • b. Campylobacter antitoxin
    • c. Ciprofloxacin
    • d. Erythromycin
    • e. Pepto-Bismol
  24. An outbreak of postsurgical wound infections caused by staphylococcu aureus has occurred. The infection control team wsa asked to determine whether the organism could be carried by one of the operating room personnel. Using your knowledge of normal flora, which on eof the following body sites is the MOST likely location for this organism?
    • Colon
    • Gingival crevice
    • Nose
    • Throat
    • Vagina
  25. Several Neisseria species are a part of the normal flora (commensals) of the human upper respiratory tract. Which of the following statements accurately describes the significance of these bacteria?
    • a. As a part of the normal flora, Neisseriae provide a natural immunity in local host defense
    • b. As a part of the respiratory flora, they are the most common cause of acute bronchitis and pneumonia
    • c. Commensal bacteria stimulate a cell-mediated immunity (CMI)
    • d. Commensal Neisseriae in the upper respiratory tract impede phagocytosis by means of lipoteichoic acid
    • e. Normal flora such as nonpathogenic Neisseriae provide effective nonspecific B-cell-mediated humoral immunity
  26. A 60-year-old female complains of tenderness and pain around a peritoneal catheter. Blood cultures reveal gram-positive, catalase-positive cocci. Which of the following is the most likely organism which is also considered a predominant organism on skin?
    • a. a-hemolytic streptococci
    • b. B. ragtlis
    • c. E. coli
    • d. Lactobacillus
    • e. S, epidermidis
  27. A 60-year-old female complains of tenderness and pain around a peritoneal catheter. Blood cultures reveal gram-positive, catalase-positive cocci. Which of the following is the most likely organism which is also considered a predominant organism on skin?
    • a. a-hemolytic streptococci
    • b. B. ragtlis
    • c. E. coli
    • d. Lactobacillus
    • e. S, epidermidis
  28. A 65-year-old woman had symptoms of dementia. An MRI revealed significant cortical atrophy. It was determined that her intraventricular pressure was very high, and a ventriculoperitoneal shunt (from the brain, tunneling under the skin into the peritoneal cavity) was placed to relieve the pressure. Three weeks later she developed a fever to 38°C, malaise, and anorexia but no other symptoms. Of the following, which one BEST describes MOST likely organism causing her current symptoms?
    • a. A gram-positive coccus that does not clot plasma
    • b. A curved gram-negative rod that produces urease
    • c. An acid-fast rod that does not grow on bacteriologic media
    • d. An obligate intracellular parasite that forms a cytoplasmic inclusion body
    • e. A spirochete that induces an antibody that agglutinates a lipid from a cow's heart
  29. A 25-year-old man was in a motorcycle accident 3 days ago, in which he sustained severe head trauma. He has had spinal fluid leaking from his nose since the accident and now develops a severe headache. His temperature is 39°C, and on examination you find nuchal rigidity. You do a lumbar puncture and find that the spinal fluid is cloudy and contains 5000 WBC/|o,L, 90% of which are polys. Of the following, which one is the MOST likely result observed in the laboratory analysis of the spinal fluid?
    • a. Gram-negative rods that grew only anaerobically
    • b. A motile spirochete that formed p-hemolytic colonies on blood agar
    • c. Gram-positive cocci that formed a-hemolytic colonies on blood agar
    • d. Gram-positive cocci that grew only in the presence of 6.5% sodium chloride
    • e. Gram-positive rods that grew only on chocolate agar supplemented with X and V factors
    • f. No organism was seen using Gram stain, but tissue stains revealed cytoplasmic inclusion bodies
  30. Your patient is a 10-year-old girl who has leukemia and is receiving chemotherapy through an indwelling venous catheter. She now has a fever of 39°C but is otherwise asymptomatic. You do a blood culture, and the laboratory reports growth of Staphylococcus epidermidis. Which one of the following results is LEAST likely to be found by the clinical laboratory?
    • a. Gram-positive cocci in clusters were seen on Gram stain of the blood culture
    • b. Subculture of the blood culture onto blood agar revealed non-hemolytic colonies
    • c. A coagulase test on the colonies was negative
    • d. A catalase test on the colonies was negative
  31. A 60-year-old woman had surgery for ovarian carcinoma 4 days ago and has an indwelling urinary catheter in place. She now spikes a fever to 39°C and has cloudy urine in the collection bottle. Gram stain of the urine shows many polys and gram-positive cocci in chains. Which one of the following would be the MOST likely findings in the urine culture?
    • a. Hemolytic colonies on the blood agar plate that are optochin-sensitive
    • b. Hemolytic colonies on the blood agar plate that are bacitracin-sensitive
    • c. Nonhemolytic colonies on the blood agar plate that hydrolyze hippurate
    • d. Nonhemolytic colonies on the blood agar plate that grow in 6.5% sodium chloride
  32. A 40-year-old male had been in good health until he began experiencing a chronic cough. Over the following 6 weeks the cough gradually worsened and became productive. He also noted weight loss, fever, night sweats, and coughing blood. A sputum sample was positive for acid-fast bacilli. Which of the following pathogenic mechanisms can be primarily attributed to the etiologic agent involved in this disease?
    • a. Cell-mediated hypersensitivity
    • b. Clogging of alveoli by large numbers of acid-fast mycobacteria
    • c. Humoral immunity
    • d. Specific cell adhesion sites
    • e. Toxin production by the mycobacteria
  33. Your patient is a 6-year-old boy with papular and pustular skin lesions on his face. A serous, "honey-colored" fluid exudes from the lesions. You suspect impetigo. A Gram stain of the pus reveals many neutrophils and gram-positive cocci in chains.If you cultured the pus on blood agar, which one of the following
would you be MOST likely to see?
    • a. Small B-hemolytic colonies containing bacteria that are bacitracin-sensitive
    • b. Small a-hemolytic colonies containing bacteria that are resistant to optochin
    • c. Large nonhemolytic colonies containing bacteria that are oxidase-positive
    • d. Small nonhemolytic colonies containing bacteria that grow in 6.5% NaCl
  34. Your patient is a 3-year-old girl with fever and pain in her right ear. On physical examination, the drum is found to be perforated and a bloody exudate is seen. A Gram stain of the exudate reveals gram-positive diplococci. Of the following, which one is the MOST likely cause?
    • a. Streptococcus pyogenes
    • b. Staphylococcus aureus
    • c. Corynebacterium diphtheriae
    • d. Streptococcus pneumoniae
  35. Your patient is a 15-year-old boy with migratory polyarthritis, fever, and a new, loud cardiac murmur. You make a clinical diagnosis of rheumatic fever. Which one of the following laboratory results is MOST likely to be found in this patient?
    • a. A blood culture is positive for Streptococcus pyogenes at this time
    • b. A throat culture is positive for Streptococcus pyogenes at this time
    • c. A Gram stain of the joint fluid shows gram-positive cocci in chains at this time
    • d. An anti-streptolysin O assay is positive at this time
  36. Your patient is a 20-year-old man who was in a fist fight and suffered a broken jaw and lost two teeth. Several weeks later, he developed an abscess at the site of the trauma that drained to the surface of the skin, and yellowish granules were seen in the pus. Regarding this disease, which one of the following is MOST
accurate?
    • a. The causative organism is a gram-positive rod that forms long filaments
    • b. The causative organism is a comma-shaped gram-negative rod that produces an exotoxin which increases
cyclic AMP
    • c. The causative organism cannot be seen in the Gram stain but can be seen in an acid-fast stain
    • d. A combination of gram-negative cocci and spirochetes cause this disease
  37. Your patient is a 70-year-old woman who had a hysterectomy for carcinoma of the uterus 3 days ago. She has an indwelling urinary catheter in place and now has a fever to 39°C, and the urine in the collection bottle is cloudy. A Gram stain of the urine specimen shows many neutrophils and gram-positive cocci in chains. You also do a urine culture. Which one of the following is the MOST likely set of findings on the urine culture?
    • a. b-Hemolytic colonies that are bacitracin-sensitive
    • b. b-Hemolytic colonies that are optochin-sensitive
    • c. Nonhemolytic colonies that grow in 6.5% sodium chloride
    • d. Nonhemolytic colonies that grow only anaerobically
  38. Your patient is a 10-year-old girl who has had pain in her left arm for the past 5 days. On physical examination, her temperature is 38°C and there is tenderness of the humerus near her deltoid. On X-ray of the humerus, an area of raised periosteum and erosion or bone is seen. You do a blood culture. Which one of the following is the MOST likely set of findings'
    • a. Gram-negative rods that grow on EMB agar, forming purple colonies and a green sheen
    • b. Gram-positive cocci that grow on blood agar, causing a clear zone of hemolysis, and are coagulase-positive
    • c. Gram-positive rods that grow only anaerobically and form a double zone of hemolysis on blood agar
    • d. Gram-negative diplococci that grow on blood agar, are oxidase-positive, and ferment maltose
  39. Your patient is a 10-year-old boy who is receiving chemotherapy for acute leukemia. He develops fever, headache, and stiff neck, and you make a presumptive diagnosis of meningitis i~-do a lumbar puncture. A Gram stain reveals a small gram-positive rod, and culture of the spinal fluid grows a beta-hemolytic colony of blood agar. Regarding this organism, which one of the following is MOST accurate?
    • a. It has more than 100 serologic types
    • b. It produces an exotoxin that inhibits elongation factor 2
    • c. It is commonly acquired by eating unpasteurized dairy products
    • d. There is a toxoid vaccine available against this organism
  40. Ms. Jones calls to say that she, her husband, and their child have had nausea and vomiting for the past hour or so. Also, they have had some nonbloody diarrhea. You ask when their last meal together was, and she says they had a picnic lunch in the park about 3 hours ago. They have no fever. Which one of the following is the MOST likely finding?
    • a. Gram stain of the leftover food would show many gram-positive cocci in clusters
    • b. Gram stain of the stool would show many gram-negative diplococci
    • c. KOH prep of the leftover food would show many budding yeasts
    • d. Acid-fast stain of the stool would show many acid-fast rods
  41. A 4-week-old newborn develops meningitis. Short, gram-positive rods are isolated. History reveals that the mother had eaten unpasteurized cheese from Mexico during the pregnancy, and she recalled having a flu like illness. Which of the following is the most likely etiologic microorganism?
    • a. C. diphtheriae
    • b. E. coli
    • c. Group B streptococci
    • d. Listeria monocytogenes
    • e. S. pneumnoniae
  42. A patient appears in the emergency room with a submandibular mass. A smear is made of the drainage and a bewildering variety of bacteria are seen, including branched, gram-positive rods. Which of the following is the most clinically appropriate action?
    • a. Consider vancomycin as an alternative drug
    • b. Determine if fluorescent microscopy is available for the diagnosis of actinomycosis
    • c. Do no further clinical workup
    • d. Suggest to the laboratory that low colony counts may reflect infection
    • e. Suggest a repeat antibiotic susceptibility test
  43. A patient complains to his dentist about a draining lesion in his mouth. A Gram stain of the pus shows a few gram-positive cocci, leukocytes, and many-branched gram-positive rods. Branched yellow sulfur granules are observed by microscopy. Which of the following is the most likely cause of the disease?
    • a. Actinomyces israelii
    • b. Actinomyces viscosus
    • c. C. diphtheriae
    • d. Propionibacterium acnes
    • e. S. aureus
  44. A 2-year-old child has a high fever and is irritable. He has a stiff neck. ( i ram stain smear of spinal fluid reveals gram-negative, small pleomorphic coccobacillary organisms. What is the most appropriate procedure to follow in order to reach an etiological diagnosis?
    • a. Culture the spinal fluid in chocolate agar, and identify the organism by growth factors
    • b. Culture the spinal fluid in mannitol-salt agar
    • c. Perform a catalase test of the isolated organism
    • d. Perform a coagulase test with the isolate
    • e. Perform a latex agglutination (LA) test to detect the specific antibody in the spinal fluid
  45. A severely burned firefighter develops a rapidly disseminating bacterial infection while hospitalized. "Green pus" is noted in the burned tissue, and cultures of both the tissue and blood yield small, oxidase-positive, gram-negative rods. Which of the following statements about this organism is correct?
    • a. Endotoxin is the only virulence factor known to be produced by these bacteria
    • b. Humans are the only known reservoir hosts for these bacteria
    • c. The bacteria are difficult to culture because they have numerous growth requirements
    • d. These are among the most antibiotic resistant of all clinically relevant bacteria
    • e. These highly motile bacteria can "swarm" over the surface of culture media
  46. Several days after an unprotected sexual encounter, a healthy 21 year-old male develops pain and pus on urination. A Gram stain revealed gram-negative diplococci. Which of the following structures is responsible for adherence of the offending microbe to the urethral mucosa?
    • a. Capsule
    • b. Fimbriae
    • c. Flagella
    • d. The F pili
    • e. The peptidoglycan
    • f. The lipopolysaccharide (LPS)
  47. A 2-year-old boy who missed several scheduled immunizations presents to the emergency room with a high fever, irritability, and a stiff neck. Fluid from a spinal tap reveals 20,000 white blood cells WBCs per mL with 85% polymorphonuclear cells. Gram stain evaluation of the fluid reveals small pleomorphic gram-negative rods that grow on chocolate agar. If an inhibitor is designed to block its major virulence, which of the following would be the most likely target?
    • a. Capsule formation
    • b. Endotoxin assembly
    • c. Exotoxin liberator
    • d. Flagella synthesis
    • e. IgA protease synthesis
    • f. H influenzae
  48. Your patient is a 70-year-old man with a long history of smoking who now has a fever and a cough productive of greenish sputum. You suspect pneumonia, and a chest X-ray confirms your suspicion. If a Gram stain of the sputum reveals very small gram-negative rods and there is no growth on a blood agar but colonies do
grow on chocolate agar supplemented with NAD and heme, which one of the following bacteria is the MOST likely cause?
    • a. Chlamydia pneumoniae
    • b. Legionella pneumophila
    • c. Mycoplasma pneumoniae
    • d. Haemophilus influenzae
  49. Your patient is a 20-year-old woman with the sudden onset of fever to 104°F and a severe headache. Physical examination reveals nuchal rigidity. You suspect meningitis and do a spinal tap. Gram stain of the spinal fluid reveals many neutrophils and many gram-negative diplococci. Of the following bacteria, which one is MOST likely to be the cause?
    • a. Haemophilus influenzae
    • b. Neisseria meningitidis
    • c. Streptococcus pneumoniae
    • d. Pseudomonas aeruginosa
  50. Your patient is a 6-year-old boy with a history of several episodes of pneumonia. A sweat test revealed an increased amount of chloride, indicating that he has cystic fibrosis. He now has a fever and is coughing up a thick, greenish sputum. A Gram stain of the sputum reveals gram-negative rods. Of the following, which one is the MOST likely organism to cause this infection?
    • a. Pseudomonas aeruginosa
    • b. Haemophilus influenzae
    • c. Legionella pneumophila
    • d. Bordetella pertussis
  51. Your patient is a 28-year-old man with third-degree burns over a large area of his back and left leg. This morning, he spiked a fever to 40°C and had two teeth-chattering chills. A blood culture grows a gram-negative rod that is oxidase-positive and produces a blue-green pigment. Of the following, which one is the MOST likely organism to cause this infection?
    • a. Prevotella melaninogenica
    • b. Pseudomonas aeruginosa
    • c. Proteus mirabilis
    • d. Haemophilus influenza
  52. A 70-year-old woman has sustained third-degree bums over a Significant area of her body. Despite appropriate burn care in the hospital, she spiked a fever to 39°C, and the nurse reports blue-green pus on the dressing covering the burned area. Gram stain of the pus reveals gram-negative rods, and antibiotic sensitivity tests show resistance to most antibiotics. Which one of the following organisms is MOST likely to cause this disease?
    • a. Nocardia astemides
    • b. Vibrio vulnificus
    • c. Bacteroidesfragilis
    • d. Haemophilus influenzas
    • e. Pseudomonas aeruginosa
  53. Your patient is a 30-year-old man with acute onset of fever to 40°C and a swollen, very tender right femoral node. His blood pressure is 90/50, and his pulse is 110. As you examine him, he has a teeth-chattering shaking chill. He returned from a camping trip in the Southern California desert 2 days ago. Regarding this disease, which one of the following is MOST accurate?
    • a. An aspirate of the node will reveal a small gram-negative rod
    • b. The organism was probably acquired by eating food contaminated with rodent excrement
    • c. The aspirate of the node should be cultured on Lowenstein-Jensen agar and an acid-fast stain performed
    • d. The organism causes disease primarily in people with impaired cell-mediated immunity
  54. A 55-year-old man who is being treated for adenocarcinoma of the lung is admitted to a hospital because of a temperature of 38.9°C (102°F), chest pain, and a dry cough. Sputum is collected. Gram stain of the sputum is unremarkable, and culture reveals many small, gram-negative rods able to grow only on a charcoal yeast extract agar. Which of the following is the most likely organism?
    • a. Chlamydia trachomatis
    • b. Klebsiella pneumonias
    • c. Legionella pneumophila
    • d. M. pneumoniae
    • e. S. aureus
  55. A severely burned firefighter develops a rapidly disseminating bacterial infection while hospitalized. "Green pus" is noted in the burned tissue, and cultures of both the tissue and blood yield small, oxidase-positive, gram-negative rods. Which of the following statements about this organism is correct?
    • a. Endotoxin is the only virulence factor known to be produced by these bacteria
    • b. Humans are the only known reservoir hosts for these bacteria
    • c. The bacteria are difficult to culture because they have numerous growth requirements
    • d. These are among the most antibiotic resistant of all clinically relevant bacteria
    • e. These highly motile bacteria can "swarm" over the surface of culture media
  56. A 16-year-old Hispanic female with poor oral hygiene and severe gingivitis presents with a temperature of 103.5°F and hypotension. Blood culture is positive for Capnocytophaga. Which of the following statements best characterizes Capnocytophaga?
    • a. A gram-negative, pleomorphic rod that can cause endocarditis
    • b. A gram-negative rod, fusiform-shaped, that is associated with periodontal disease but may cause sepsis
    • c. The causative agent of rat-bite fever
    • d. The causative agent of sinusitis, bronchitis, and pneumonia
    • e. The causative agent of trench fever
  57. A 6-year-old boy fell and sustained a deep wound from a rusty nail that penetrated his thigh. His mother removed the nail and cleaned the wound with soap and water. The next morning, he had a temperature of 102°F, and his thigh was very painful and swollen. In the emergency room, crepitus (gas in the tissue)
was noted. A Gram stain of exudate from the wound area revealed large gram-positive rods. Which one of the following is the MOST likely cause?
    • a. Actinomyces israelii
    • b. Clostridium perfringens
    • c. Clostridium tetani
    • d. Listeria monocytogenes
    • e. Mycobacterium fortuitum-chelonei complex
    • f. Nocardia asteroides
    • g. Pseudomonas aeruginosa
  58. A 70-year-old woman has the rapid onset of fever to 39°C and a cough productive of greenish sputum. She is not hospitalized and not immunocompromised. A chest X-ray reveals a left lower lobe infiltrate. Of the following, which set of findings describes the MOST likely causative organism found in the sputum culture?
    • a. Gram-positive diplococci that form an a-hemolytic colony
    • b. Gram-negative diplococci that form an oxidase-positive colony
    • c. Gram-positive rods that form a 3-hemolytic colony
    • d. Gram-negative rods that form an oxidase-positive colony
    • e. Gram-negative cocci that grow only anaerobically
  59. A 25-year-old pregnant woman in the third trimester comes to the emergency room saying that about 12 hours ago she began to feel feverish and weak. On examination, she has a temperature of 40°C but no other pertinent findings. A blood culture grows small gram-positive rods that cause (3-hemolysis on a blood
agar plate incubated in room air. Which one of the following bacteria is the MOST likely cause?
    • a. Clostridium perfringens
    • b. Streptococcus pyogenes
    • c. Bacillus cereus
    • d. Listeria monocytogenes
    • e. Brucella abortus
  60. Streptococcus mutans is best described by which of the following statements?
    • a. An anaerobic, filamentous bacterium that often causes cervicofacial osteomyelitis
    • b. A beta hemolytic organism that causes a diffuse, rapidly spreading cellulitis
    • c. A facultative anaerobe that is highly cariogenic and sticks to teeth by synthesis of a dextran
    • d. A facultative anaerobe that often inhabits the buccal mucosa early in a neonate's life and can cause bacterial endocarditis
    • e. A facultatively anaerobic, rod-shaped bacterium that sticks to teeth and is cariogenic
  61. Streptococcus salivarius, a common isolate in the clinical laboratory, is best described by which of the following statements?
    • a. An anaerobic, filamentous bacterium that often causes cervicofacial osteomyelitis
    • b. A beta-hemolytic organism that causes a diffuse, rapidly spreading cellulitis
    • c. A facultative anaerobe that is highly cariogenic and sticks to teeth by synthesis of a dextran
    • d. A facultative anaerobe that often inhabits the buccal mucosa early in a neonate's life and can cause bacterial endocarditis
    • e. A facultatively anaerobic, rod-shaped bacterium that sticks to teeth and is cariogenic
  62. A patient was hospitalized after an automobile accident. The wounds became infected, and the patient was treated with tobramycin, carbenicillin, and clindamycin. Five days after antibiotic therapy was initiated, the patient developed severe diarrhea and pseudomembranous enterocolitis. Antibiotic-associated diarrhea and the more serious pseudomembranous enterocolitis can be caused by which of the following organisms?
    • a. B.fragilis
    • b. Clostridium difficile
    • c. Clostridium perfringens
    • d. Clostridium sordellii
    • e. S. aureus
  63. Your patient is a 27-year-old woman who was treated with oral ampicillin for cellulitis caused by Streptococcus pyogenes. Several days later, she developed bloody diarrhea. You suspect that she may have pseudomembranous colitis. Regarding the causative organism of pseudomembranous colitis, which one of the following is the MOST accurate?
    • a. It is an anaerobic gram-positive rod that produces exotoxins
    • b. It is a comma-shaped gram-negative rod that grows best at 41°C
    • c. It is an obligate intracellular parasite that grows in cell culture but not on blood agar
    • d. It is a yeast that forms germ tubes when incubated in human serum at 37°C
  64. Your patient is a 70-year-old man with a fever of 40°C and a very painful cellulitis of the right buttock. The skin appears necrotic, and there are several fluid-filled bullae. Crepitus can be felt, indicating gas in the tissue. A Gram stain of the exudate reveals large gram-positive rods. Of the following, which one is the MOST likely cause?
    • a. Clostridium perfringens
    • b. Bacillus anthracis
    • c. Corynebacterium diphtheriae
    • d. Actinomyces israelii
  65. Several hours after dining on sweet and sour chicken and pork fried rice at the home of an Asian friend, a 34-year-old car salesman exhibits abdominal discomfort, nausea, and vomiting. In the middle of the night he awakens with watery diarrhea. Which of the following pairs of organisms is routinely responsible for food poisoning?
    • a. Clostridium botulinum and Bacillus anthracis
    • b. C. difficile and C. botulinum
    • c. C. perfringens and Bacillus cereus
    • d. C. tetani and B. anthracis
    • e. Clostridium t. and B. cereus
  66. One of the bacteria isolated from the foul-smelling exudates taken from an abscess is missing superoxide dismutase, catalase, and a peroxidase.Which of the following statements best describes this microorganism?
    • a. Aminoglycoside antibiotics will be effective against this bacterium
    • b. This bacterium is a facultative aerobe
    • c. This bacterium is an anaerobe
    • d. This bacterium is more virulent than one containing the three enzymes
    • e. This bacterium will survive in an O2 environment
  67. A 25-year-old medical student presented with a ruptured appendix. A peritoneal infection developed, despite prompt removal of the organ and extensive flushing of the peritoneal cavity. An isolate from a pus culture was a gram-negative rod identified as Bacteroides fragilis. Anaerobic infection with B. fragilis is best characterized by which of the following?
    • a. A black exudate in the wound
    • b. A foul-smelling discharge
    • c. A heme-pigmented colony formation
    • d. An exquisite susceptibility to penicillin
    • e. Severe neurologic symptoms
  68. A 17-year-old man is hospitalized with trauma to the abdomen following a gang-related fight. He develops an intra-abdominal abscess, which is drained and sent to the laboratory. A mixture of gram-negative anaerobes are detected. Which of the following microorganisms is the most likely and is also the most prevalent bacterium in the gut?
    • a. a-Hemolytic Streptococci
    • b. B.fragilis
    • c. E. coli
    • d. Lactobacillus
    • e. S. epidermidis
  69. Your patient is a 62-year-old woman with a history of carcinoma of the sigmoid colon that was removed 5 days ago. The surgery was complicated by the escape of bowel contents into the peritoneal cavity. She now has fever and pain in the perineum and left buttock. On physical examination, her temperature is 39°C and myonecrosis with a foul-smelling discharge is found. A Gram stain of the exudate reveals gram-negative rods. Of the following, which one is the MOST likely organism to cause this infection?
    • a. Helicobacter pylori
    • b. Bacteroides fmgilis
    • c. Salmonella typhi
    • d. Vibrio parahaemolyticus
  70. Your patient is a 30-year-old woman who was part of a tour group visiting a Central American country. The day before leaving, several members of the group developed fever, abdominal cramps, and bloody diarrhea.Of the following, which one is the LEAST likely organism to cause this infection?
    • a. Shigella dysenteriae
    • b. Salmonella enteritidis
    • c. Vibrio cholerae
    • d. Campylobacter jejuni
  71. A stool culture reveals no lactose-negative colonies on the EMB agar. Which one of the following is the MOST likely organism to cause this infection?
    • a. Shigella dysenteriae
    • b. Salmonella enteritidis
    • c. Vibrio cholerae
    • d. Campylobacter jejuni
  72. Your patient is a 55-year-old man with severe cellulitis of the right leg, high fever, and a teeth-chattering chill. He is a fisherman who was working on his boat in the waters off the Texas coast yesterday.Which one of the following organisms is MOST likely to be the cause of his disease?
    • a. Yersinia pestis
    • b. Vibrio vulnificus
    • c. Pasteurella multocida
    • d. Brucella melitensi
  73. Your patient is a 5-year-old girl with bloody diarrhea and no vomiting. There is no history of travel outside of San Francisco. Stool culture grows both lactose-positive and lactose-negative colonies on EMB agar.Of the following organisms, which one is MOST likely to be the cause?
    • a. Shigella sonnei
    • b. Salmonella typhi
    • c. Campylobacter jejuni
    • d. Helicobacter pylori
  74. Your patient is a 50-year-old woman who returned yesterday from a vacation in Peru, where there is an epidemic of cholera. She now has multiple episodes of diarrhea. Of the following, which one is MOST compatible with cholera?
    • a. Watery diarrhea without blood, no polys in the stool, and growth of curved gram-negative rods in the blood culture
    • b. Watery diarrhea without blood, no polys in the stool, and no organisms in the blood culture
    • c. Bloody diarrhea, polys in the stool, and growth of curved gram-negative rods in the blood culture
    • d. Bloody diarrhea, polys in the stool, and no organisms in the blood culture
  75. Your patient is a 40-year-old woman with a severe attack of diarrhea that began on the airplane while she was returning from a vacation in the Middle East. She had had multiple episodes of watery. nonbloody diarrhea and little vomiting. She is afebrile. A stool culture reveals only lactose-fermenting colonies on EMB agar. Of the following, which one is the MOST likely cause?
    • a. Shigella sonnei
    • b. Helicobacter pylori
    • c. Escherichia coli
    • d. Pseudomonas aeruginosa
  76. Ten boy scouts are hospitalized with bloody diarrhea and severe hematological abnormalities. An investigation establishes that all of the boys developed symptoms following consumption of hamburgers from the same fast-food restaurant chain. Which of the following best describes E. coli 0157/H7, the etiologic bacterium responsible for the outbreak?
    • a. It produces at least one protein toxin consisting of two subunits, A and B, that cause severe spasmodic cough, usually in children
    • b. It produces a toxin that blocks protein synthesis in an infected cell and carries a lytic bacteriophage that produces the genetic information for toxin production
    • c. It secretes an erythrogenic toxin that causes the characteristic signs of scarlet fever
    • d. It secretes an exotoxin that has been called "verotoxin" and "Shiga-like toxin"; infection is mediated by specific attachment to mucosal membranes It requires cysteine for growth
  77. A 65-year-old healthy retired former executive female went on her yearly vacation to Mexico. Unlike her previous trips she decided to use the local water to make her favorite punch. Thirty-six hours later she developed profused watery diarrhea, severe cramping, and abdominal pain. She was diagnosed with E. coli related diarrhea. Which of the following E. coli types is characterized by the presence of heat-labile (LT) and heat-stable (ST) proteins?
    • a. Enteroinvasive (EIEC)
    • b. Enterotoxigenic (ETEC)
    • c. Enterohemorrhagic (EHEC)
    • d. Enteropathogenic (EPEC)
    • e. Enterohemolytic (EHEEC)
  78. Your patient is a 20-year-old woman with severe diarrhea that began yesterday. She has just returned from a 3 week trip to Peru, where she ate some raw shellfish at the farewell party. She now has watery diarrhea, perhaps 20 bowel movements a day, and is feeling quite weak and dizzy. Her stool is guaiac-negative, a test that determines whether there is blood in the stool. A Gram stain of the stool reveals curved gram-negative rods. Of the following organisms, which one is MOST likely to be the cause of her diarrhea?
    • a. Bacteroidesfragilis
    • b. Campylobacterjejuni
    • c. Entamoeba histolytica
    • d. Helicobacterpylori
    • e. Shigella dysenteriae
    • f. Vibrio cholerae
    • g. Yersinia enterocolitica
  79. Several hours after dining on sweet and sour chicken and pork fried rice at the home of an Asian friend, a 34-year-old car salesman exhibits abdominal discomfort, nausea, and vomiting. In the middle of the night he awakens with watery diarrhea. Which of the following pairs of organisms is routinely responsible for food poisoning?
    • a. Clostridium botulinum and Bacillus anthracis
    • b. C. difficile and C. botulinum
    • c. C. perfringens and Bacillus cereus
    • d. C. tetani and B. anthracis
    • e. Clostridium t. and B. cereus
  80. A 40-year-old female reports chronic gastritis. She tests positive for H. pylori. After a course of the appropriate antibiotic therapy her symptoms subside. Which of the following is the most effective noninvasive test for the diagnosis of Helicobacter -associated gastric ulcers?
    • a. Culture of stomach contents for H. pylon
    • b. Detection of H. pylori antigen in stool
    • c. Growth of H. pylori from a stomach biopsy
    • d. Growth of H. pylori in the stool
    • e. IgM antibodies to H. pylori
  81. Although cholera, a Vibrio infection, has rarely been seen in the USA , there have been recent outbreaks of classic cholera associated with shellfish harvested from the Gulf of Mexico. Vibrios are shaped like curved rods, and infections more common than cholera may be caused by a variety of curved-rod bacteria. Which of the following best describes C jejuni?
    • a. Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42 degree C
    • b. Human pathogen, halophihc, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of under-cooked seafood
    • c. Human pathogen, halophilic, lactose-positive; produces heat-labile,toxin
    • d. "String-test"—positive isolate; three serotypes—Ogawa (AB), Inaba (AC)Hikojima (ABC) Urease-positive; cause of fetal distress in cattle
  82. A box of ham sandwiches with mayonnaise, prepared by a person with a boil on his neck, was left out of the refrigerator for the on-call interns. Three doctors became violently ill approximately 2 hours after eating the sandwiches. Which of the following is the most likely cause?
    • a. C. perfringens toxin
    • b. Coagulase from S. aureus in the ham
    • c. Penicillinase given to inactivate penicillin in the pork
    • d. S. aureus enterotoxin
    • e. S. aureus leukocidin
  83. An 80-year-old man had a carcinoma of the colon removed 3 days ago. He was doing well until this morning, when he spiked a fever to 39°C and complained of severe abdominal pain. Examination revealed a "boardlike" abdomen indicative of peritonitis. He was taken to the operating room, where it was discovered that his anastomosis had broken down and bowel contents had spilled into the peritoneal cavity. A foul-smelling exudate was observed. A Gram stain of the peritoneal exudate revealed many gram-negative rods. Which one of the following sets of bacteria is the MOST likely cause of this infection?
    • a. Escherichia coli and Brucella melitensis
    • b. Enterobacter cloacae and Salmonella enteritidis
    • c. Fusobacterium nudeatum and Bacteroides fragilis
    • d. Haemophilus influenzae and Actinomyces israelii
    • e. Shigella dysenteriae and Serratia marcescens
  84. A patient with a burning epigastric pain was admitted to the hospital, and a gastric biopsy was performed. The tissue was cultured on chocolate agar incubated in a microaerophilic environment at 37°C for 5-7 days. At 5 days of incubation, colonies appeared on the plate and curved, gram-negative rods, oxidase-positive, were observed. Which of the following is the most likely identity of this organism?
    • a. Campylobacterfetus,
    • b. Campylobacterjejuni
    • c. Haemophilus influenzae
    • d. Helicobacter pylori
    • e. Vibrio parahaemolyticus
  85. A patient was hospitalized after an automobile accident. The wounds became infected, and the patient was treated with tobramycin, carbenicillin, and clindamycin. Five days after antibiotic therapy was initiated, the patient developed severe diarrhea and pseudomembranous enterocolitis. Antibiotic-associated diarrhea and the more serious pseudomembranous enterocolitis can be caused by which of the following organisms?
    • a. B.fragilis
    • b. Clostridium difficile
    • c. Clostridium perfringens
    • d. Clostridium sordellii
    • e. S. aureus
  86. An outbreak occurred in a community where the water supply was contaminated. Multiple patients experienced nausea and vomiting, as well as profuse diarrhea with abdominal cramps. Stools were described as "rice water." Curved, gram-negative rods were isolated on this sulfate-citrate-bile-sucrose agar. In the treatment of patients who have cholera, the use of a drug that inhibits adenyl cyclase would be expected to have which of the following characteristics?
    • a. Block the action of cholera toxin
    • b. Eradicate the organism
    • c. Increase fluid secretion
    • d. Kill the patient immediately
    • e. Reduce intestinal motility
  87. Two of three family members had dinner at a local restaurant and, within 48 hours, experienced double vision, difficulty in swallowing and speaking, and breathing problems. These symptoms are consistent with which of the following?
    • a. Activation of cyclic AMP
    • b. Endotoxin shock
    • c. Ingestion of a neurotoxin
    • d. Invasion of the gut epithelium by an organism
    • e. Secretion of an enterotoxin
  88. Testing of an isolate possesses the group D antigen, and is not beta -lactamase-positive, but is resistant to vancomycin. Which of the following is the most likely identification of this isolate?
    • a. Enterococcus cassiflavus
    • b. Enterococcus durans
    • c. Enterococcus faecalis
    • d. Enterococcus faecium
    • e. S. pneumonia
  89. Which of the following is the treatment of choice for the isolate in question 216?
    • a. Ciprofloxacin
    • b. Gentamicin
    • c. Gentamicin and ampicillin
    • d. Rifampin
    • e. No available treatment
  90. A family routinely consumed unpasteurized milk, claiming "better taste." Several members experienced a sudden onset of crampy abdominal pain, fever, and bloody, profuse diarrhea. C. jejuni was isolated and identified from all patients. Which of the following is the treatment of choice for this type of enterocolitis?
    • a. Ampicillin
    • b. Campylobacter antitoxin
    • c. Ciprofloxacin
    • d. Erythromycin
    • e. Pepto-Bismol
  91. V cholerae, the causative agent of cholera, is best described by which of the following statements?
    • a. Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42 °
    • b. Human pathogen, halophilic, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of under-cooked seafood
    • c. Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin
    • d. "String-test"—positive isolate; three erotypes—Ogawa (AB), Inaba (AC),Hikojima (ABC)
    • e. Urease-positive; cause of fetal distress in cattle
  92. A 20-year-old female in post-Katerina New Orleans eats poorly cooked seafood (oysters, clams, and mollusks) for her birthday dinner. Twenty-four hours later, she develops explosive watery diarrhea and abdominal cramps. She is positive for V parahaemolyticus. Which of the following statements best describes this organism?
    • a. Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42° C
    • b. Human pathogen, halophilic, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of under-cooked seafood
    • c. Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin
    • d. "String-test"—positive isolate; three serotypes—Ogawa (AB), Inaba (AC),Hikojima (ABC)
    • e. Urease-positive; cause of fetal distress in cattle
  93. Twenty-four hours after returning from a short trip to Asia, a 35-year-old female has a sudden onset of vomiting and massive watery diarrhea that is colorless, odorless, and contains flecks of mucus. Which of the following mediums would most likely be used for isolating V cholerae, the suspected organism?
    • a. A Lofflers medium
    • b. B Lowenstein-Johnson medium
    • c. C Sheep blood agar
    • d. D Thayer Martin
    • e. E Thiosulfate citrate bile salts sucrose medium
  94. A 31-year-old school teacher returns from foreign travel and experiences a sudden (1-2 days) onset of abdominal pain, fever, and watery diarrhea, caused by a heat-labile exotoxin that affects both the gut and the NS. This infection is caused by an etiologic agent commonly acquired through which of the following routes?
    • a. Gastrointestinal tract
    • b. Genital tract
    • c. Nasal tract
    • d. Respiratory tract Skin
  95. An HIV-positive patient has progressed from fatigue, rash, nausea, and night sweats symptoms to occasional but defined opportunistic infections. I k inquires as to what can be done to predict his chances of developing I) Diplomatic AIDS. Which of the following tests would be most useful?
    • a. CD4 lymphocyte count
    • b. HIV antibody test
    • c. HIV p24 antigen
    • d. HIVRTPCR
    • e. Neopterin
  96. A 9-year-old male presents with fever and nonspecific symptoms followed by a distiinctive rash on the cheeks (slapped cheek). Which of the following viruses is the most likely cause of this disease and has been associated with transient aplastic crises in persons with sickle cell disease? a. Herpes simplex
    • a. Parvovirus B19
    • b. Rubella
    • c. Rubeola
    • d. Varicella-zoster
  97. A 20-year-old female presents to her physician with a low-grade fever, headache, and painful genital lesions. Culture detects herpes simplex virus (HSV). Which of the following statements best describes infection with this common human pathogen?
    • a. Infection with type 1 virus is most common
    • b. Initial infection usually occurs by intestinal absorption of the virus
    • c. It can be reactivated by emotional disturbances or prolonged exposure to sunlight
    • d. It rarely recurs in a host who has a high antibody titer
    • e. The central nervous system (CNS) and visceral organs are usually involved
  98. An HIV-positive patient, prior to being treated with AZT, DDI, and saquinavir, has a CD4 lymphocyte count and an HIV RNA viral load test done. Results are as follows:CD4: 50 CD4 lymphocytes per JJ.L HIV RNA: 100,000 copies per ml Which of the following statements best describes this patient?
    • a. This patient is no longer in danger of opportunistic infection
    • b. The 5-year prognosis is excellent
    • c. The patient's HIV screening test is most likely negative
    • d. The patient is not infectious
    • e. The viral load of 100,000 copies per milliliter suggests that the patient will respond to triple therapy
  99. An HIV-positive patient with a viral load of 100,000 copies of HIV RNA/milliliter and a total CD4 count of 50 is at increased risk for a number of infectious diseases. For which of the following diseases is the patient at no more added risk than an immunocompetent host?
    • a. Herpes simplex virus
    • b. Kaposi sarcoma
    • c. Mycobacterial disease
    • d. Pneumococcal pneumonia
    • e. Pneumocystic pneumonia
  100. Which of the following antiviral agents is a purine nucleoside analogue that has shown promise with Lassa fever, influenza A and B, and respiratory syncytial virus (RSV)?
    • a. Amantadine
    • b. Acyclovir
    • c. Ribavirin
    • d. Rimantadine
    • e. Vidarabine
  101. Enteric cytopathogenic human orphan viruses (echo-viruses) appear worldwide and are more apt to be found in young patients. Family studies demonstrated the ease and high frequency of transmission. Which of the following body systems is the main target of echoviruses?
    • a. Bladder and urinary tract
    • b. Blood and lymphatic systems
    • c. Central nervous system
    • d. Intestinal tract
    • e. Respiratory system
  102. Meningitis is characterized by the acute onset of fever and stiff neck. Aseptic meningitis may be caused by a variety of microbial agents. During the initial 24 hours of the course of aseptic meningitis, an affected person's CSF is characterized by which of the following laboratory findings?
    • a. Decreased protein content
    • b. Elevated glucose concentration
    • c. Eosinophilia
    • d. Lymphocytosis
    • e. Polymorphonuclear leukocytosis
  103. A 62-year-old Florida fisherman forgot his insect repellent on a recent sporting trip. A week later, he presented to his physician with fever, chills, headache, and flu-like symptoms that progressed to possible CNS involvement. Control of the etiologic agent, associated with a high (50-70%) fatality rate, could be possible by eradication of which of the following?
    • a. Birds
    • b. Fleas
    • c. Horses
    • d. Mosquitoes
    • e. Ticks
  104. A patient who works in an industrial setting presents to his ophthalmologist with acute conjunctivitis, enlarged and tender preauricular nodes, and early stages of keratitis. The differential diagnosis should include infection with which of the following viruses?
    • a. Adenovirus
    • b. Epstein-Barr virus
    • c. Parvovirus
    • d. Respiratory syncytial virus
    • e. Varicella-zoster virus
  105. Several antiviral compounds have been developed during the last decade. One such compound is ribavirin, a synthetic nucleoside structurally related to guanosine. Ribavirin therapy is FDA-approved for use against which of the following?
    • a. Group A coxsackievirus
    • b. Hepatitis B
    • c. Herpes simplex virus
    • d. Parvovirus
    • e. Respiratory syncytial virus
  106. An immune compromised person with a history of seizures has an MRI that reveals a temporal lobe lesion. Brain biopsy results show multinucleated giant cells with intranuclear inclusions. Which of the following is the most probable cause of the lesion?
    • a. Coxsackievirus
    • b. Hepatitis C virus
    • c. Herpes simplex virus
    • d. Listens monocytogenes
    • e. Parvovirus
  107. A 70-year-old nursing home patient refused the influenza vaccine and subsequently developed influenza. She died of acute pneumonia 1 week after contracting the flu. Which of the following is the most common cause of acute post influenzal pneumonia?
    • a. Escherichia coli
    • b. Klebsidla pneumoniae
    • c. Legionella pneumophilia
    • d. Listeria monocytogenes
    • e. Staphylococcus aureus
  108. A 5-year-old boy was sent home from kindergarten because his left eye was red with a watery, nonpurulent discharge. Several of his classmates recently had mild sore throat but no fever. Conjunctivitis lasted 1 week with complete recovery. Which of the following organisms was the most likely cause of his infection?
    • a. Adenovirus
    • b. Herpes simplex virus
    • c. Staphylococcus aureus
    • d. Chlamydiae trachomatis
    • e. Hemophilus aegypticus
  109. A husband and wife performed the yearly spring cleaning of their mountain cabin, located in the southwestern part of the United States. The wife presented to her physician 2 weeks later with fever, myalgia, headache, and nausea, followed by progressive pulmonary edema. Which of the following statements best describes the pathogen or disease progression in this patient?
    • a. Hemolysis is common in infected patients
    • b. Influenza-like symptoms are followed rapidly by acute respiratory failure
    • c. It is acquired by inhalation of aerosols of the urine and feces of deer
    • d. Transmission from human to human is common
    • e. There is effective antiviral therapy available
  110. Parvovirus infection, the cause of a mild exanthem in children, can also cause which of the following?
    • a. Aplastic crisis in chronic anemia
    • b. Epidemic acute respiratory disease
    • c. Gastroenteritis
    • d. Keratoconjunctivitis
    • e. Whooping cough-like disease
  111. Within the first year of life, an infant exhibited severe hearing loss, ocular abnormalities, and apparent mental retardation. Standard peripheral blood smears demonstrated multinucleated cells with giant nuclei and intranuclear inclusions. Which of the following statements best describes the etiologic agent?
    • a. It can be transmitted across the placental barrier
    • b. While a common infection, CMV is almost always symptomatic
    • c. The CMV can be cultured from red blood cells of infected patients
    • d. Unlike other viral infections, CMV is not activated by immunosuppressive therapy
    • e. There is no specific therapy for CMV
  112. Subacute sclerosing panencephalitis (SSPE) is characterized by inflammatory lesions and begins with mild changes in personality, ending with dementia and death. Which of the following statements best describes the disease characteristics?
    • a. Demyelination is characteristic
    • b. It is a common event occurring in 1 of 300,000 cases of mumps
    • c. It is a late CNS manifestation of mumps
    • d. It is a progressive disease involving both white and gray matter
    • e. Viral DNA can be demonstrated in brain cells
  113. The virus shown below contains double-stranded RNA within a double-walled capsid. Which of the following statements best describes this agent?
    • a. Early breast-feeding offers no protection to neonates against it
    • b. It is a major cause of neonatal diarrhea
    • c. It is readily cultured from the stool of infected persons
    • d. Maternal antibody does not appear to be protective
    • e. There are no related animal viruses
  114. Helical viruses containing negative sense linear RNA genomes and an outer lipid envelope are most commonly associated with which of the following diseases?
    • a. Croup
    • b. Fifth disease
    • c. Otitis media
    • d. Rubella
    • e. Tonsillitis
  115. A transplant patient taking high levels of immunosuppressive medications becomes infected with EBV and develops a lymphoma. The dosage of immunosuppressive drugs given to the patient is decreased, and the tumor regresses. Which of the following properties of EBV infection is related to the patient's tumor development?
    • a. Immortalization of B cells
    • b. Increased white blood cell count
    • c. Presence of atypical lymphocytes
    • d. Production of heterophile antibodie
  116. Reverse transcriptase is an enzyme found in retroviruses and hepad-naviruses. Which of the following is a function of the enzyme reverse transcriptase?
    • a. DNAse activity
    • b. DNA-dependent RNA polymerase activity
    • c. RNA-dependent DNA polymerase activity
    • d. RNA-dependent RNA polymerase activity
    • e. RNA isomerase activity
  117. Several young adults camped in a wilderness area and received multiple mosquito bites. Ten days later, one had a sudden onset of headache, chills, and fever, and became stuporous 48 hours later. He was diagnosed with Saint Louis encephalitis (SLE) and recovered completely. Which of the following best describes SLE?
    • a. It is transmitted to humans by the bite of an infected tick
    • b. It is caused by a togavirus
    • c. It is the major arboviral cause of central nervous system infection in the United States
    • d. It may present initially with symptoms similar to influenza
    • e. Laboratory diagnosis is routinely made by cultural methods
  118. There is considerable overlap of signs and symptoms seen in congenital and perinatal infections. In a neonate with classic symptoms of congenital CMV infection, which of the following tests would be most useful in establishing a diagnosis?
    • a. CMV IgG titer on neonate's serum at birth
    • b. CMV IgG titer on mother's serum at birth of infant
    • c. CMV IgM titer on neonate's serum at birth and at 1 month of age
    • d. Culture of mother's urine
    • e. Total IgM on neonate's serum at birth
  119. A 35-year-old man presents with symptoms of jaundice, right upper quadrant pain, and vomiting. His ALT is elevated. He is diagnosed with HAV infection after eating at a restaurant where others were also infected. Which of the following should be done to protect his family members?
    • a. A series of three vaccinations at 0, 1, and 6 months
    • b. Administer alpha interferon
    • c. Quarantine household contacts and observe
    • d. No treatment is necessary
    • e. One dose of gamma globulin administered intramuscularly
  120. A 17-year-old girl presents with cervical lymphadenopathy, fever, and pharyngitis. Which of the following is the most rapid and clinically useful test to make a diagnosis?
    • a. Antibody to Epstein-Barr nuclear antigen (EBNA)
    • b. C-reactive protein (CRP)
    • c. Culture
    • d. IgG antibody to viral core antigen (VCA)
    • e. IgM antibody to VCA
  121. Atypical lymphocytosis is most likely to be found in which one of the following diseases?
    • a. Encephalitis caused by herpes simplex virus (HSV)
    • b. Chronic hepatitis C
    • c. Mononucleosis induced by Epstein-Barr virus
    • d. Parvovirus infection
    • e. Rotavirus gastroenteritis
  122. A 30-year-old female with a recent history of serious illness requiring surgery developed fever, nausea, and jaundice. Her condition continued as a clinically mild disease, with AST=552, ALT=712, and the HBV panel was negative. Which one of the following statements best characterizes the illness?
    • a. Blood products are not tested for antibody to HCV
    • b. Few cases progress to chronic liver disease
    • c. HBV but not HCV infections occur in IV drug abusers
    • d. HCV is a DNA virus
    • e. HCV is the most common cause of posttransfusion hepatitis
  123. Which of the following markers is usually the first viral marker detected after hepatitis B infection?
    • a. HBcAg
    • b. HBeAg
    • c. HBsAg
    • d. HBeAb
    • e. Anti-HBc
  124. Which of the following may be the only detectable serological marker during the early convalescent phase of HBV infection (window phase)?
    • a. HBcAg
    • b. HBeAg
    • c. HBsAg
    • d. HBeAb
    • e. Anti-HBc
  125. Which of the following is found within the nuclei of infected hepa-tocytes and not usually in the peripheral circulation?
    • a. HBcAg
    • b. HBeAg
    • c. HBsAg
    • d. HBeAb
    • e. Anti-HBc
  126. An infant was born and presented with intrauterine growth retardation, jaundice, hepatosplenomegaly, microcephaly, and retinitis. Which one of the following viruses most likely caused these congenital malformations?
    • a. Cytomegalovirus
    • b. Mumps
    • c. HIV
    • d. Respiratory syncytial virus
    • e. Rubeola
  127. Which of the following specimens is best for detection of cytomegalovirus (CMV)?
    • a. Blood
    • b. Cerebrospinal fluid
    • c. Cervical tissue
    • d. Skin
    • e. Synovial fluid
  128. Which of the following specimens is best for detection of enterovirus?
    • a. Blood
    • b. Cerebrospinal fluid
    • c. Cervical tissue
    • d. Skin
    • e. Synovial fluid
  129. Which of the following specimens is best for detection of varicella-zoster virus (VZV)?
    • a. Blood
    • b. Cerebrospinal fluid
    • c. Cervical tissue
    • d. Skin
    • e. Synovial fluid
  130. Which of the following specimens is best for detection of adenovirus 40/41?
    • a. Blood
    • b. Cerebrospinal fluid
    • c. Cervical tissue
    • d. Stool
    • e. Synovial fluid
  131. Which of the following viruses causes only gastroenteritis and is the second most common cause of pediatric gastroenteritis?
    • a. Adenovirus 40/41
    • b. Astrovirus
    • c. Hepatitis A virus
    • d. Norwalk virus
c. Rotavirus
  132. Which of the following may be detected by ELISA methods or electron microscopy and is a common cause of epidemic gastroenteritis, particularly aboard cruise ships and in summer camps?
    • a. Adenovirus 40/41
    • b. Astrovirus
    • c. Hepatitis A virus
    • d. Norwalk virus
    • c. Rotavirus
  133. Unlike other similar viruses, this agent appears to account for 5-15% of the gastroenteritis in young children. Which of the following etiologic agents causes these infections and is difficult to isolate in the diagnostic
laboratory?
    • a. Adenovirus 40/41
    • b. Astrovirus
    • c. Hepatitis A virus
    • d. Norwalk virus
    • e. Rotavirus
  134. A flavivirus recently appeared in the United States with birds as the primary hosts. The virus produces viremia in humans and possible fatal encephalitis in older patients. Which of the following is this virus?
    • a. Human papillomavirus
    • b. Polyomavims
    • c. Subacute sclerosing panencephalitis (SSPE) virus
    • d. Tick-borne encephalitis virus
    • e. West Nile virus
  135. An irritable 18-month-old toddler with fever and blister-like ulcera(itions on mucous membranes of the oral cavity refuses to eat. The symptoms worsen and then slowly resolve over a period of 2 weeks. Assuming that the etiological agent was HSV type 1, which of the following statements is true?
    • a. Antivirals do not provide any benefit
    • b. The virus remains latent in the trigeminal ganglia
    • c. Recurrence is likely to result in a generalized rash
    • d. Polyclonal B cell activation is a prominent feature
    • e. The child is at high risk for developing cancer later in life
  136. A sexually active 17-year-old man presents to the local free clinic to check some small papules that appeard on his penis. The papules are small, white lesions with a central depression. There is no discharge or pain on urination. What group listed below does this etiologic agent belong to?
    • A) Adenoviridae
    • B) Arenaviridae
    • C) Papovaviridae
    • D) Parvoviridae
    • E) Poxviridae
  137. Hepatitis B virus (HBV; Hepadnaviridae), the only known gapped DNA virus to infect humans, absolutely needs which of the following polymerases in order to complete their replication cycle?
    • A) A cellular RNA-dependent RNA polymerase and reverse transcriptase
    • B) A cellular DNA-dependent RNA polymerase and reverse transcriptase
    • C) A viral RNA-dependent RNA polymerase and reverse transcriptase
    • D) A viral DNA-dependent RNA polymerase and reverse transcriptaseE) A viral RNA-dependent DNA polymerase and reverse transcriptase
  138. Retroviruses such as the Human Immunodeficiency Virus Type 1 (HIV-1) absolutely need which of the following polymerases in order to complete their replication cycle?
    • A) Reverse transcriptase and a cellular RNA-dependent RNA polymerase.
    • B) Reverse transcriptase and a viral RNA-dependent RNA polymerase.
    • C) Reverse transcriptase and a cellular DNA-dependent RNA polymerase.
    • D) Reverse transcriptase and a viral DNA-dependent RNA polymerase.
    • E) Reverse transcriptase and a viral RNA-dependent DNA polymerase.
  139. A virology research lab (Dead End Empirical Technologies Inc.) engineers a composite virus with the following characteristics: The virion possesses a capsid derived from simian virus 40 (SV40; Polyomaviridae) containing HBV (hepatitis B virus; Hepadnaviridae) gapped dsDNA, HAV (hepatitis A virus; Picornaviridae) RNA-dependent RNA polymerase, and human immunodeficiency virus type 1 (HIV-1; Retroviridae) reverse transcriptase. The nucleocapsid is surrounded by an envelope derived from HEK 293 cells (human embryonic kidney 293 cells) containing murine VSV (murine vesicular stomatitis virus; Rhabdoviridae) G proteins. If this virion were to infect permissive cells, which kind of virus would be generated?
    • A) Simian virus 40 (SV40)
    • B) Hepatitis B virus (HBV)
    • C) Hepatitis A virus (HAV)
    • D) Human immunodeficiency virus type 1 (HIV-1)
    • E) Murine vesicular stomatitis virus (VSV)
  140. Which statement best applies to virions?
    • A) Virions are the vessels that protect and deliver viral self replicating proteins from susceptible host cells to other susceptible host cells.
    • B) Virions are the vessels that protect and deliver viral self replicating proteins from permissive host cells to other permissive host cells.
    • C) Virions are vessels that protect and deliver viral genomes from susceptible host cells to other susceptible host cells.
    • D) Virions are vessels that protect and deliver viral genomes from permissive host cells to other permissive host cells.
    • E) Virions are vessels that need to be processed by viral proteases in order to become fully infectious viruses.
  141. 9) Under natural conditions (i.e. not in laboratory or immunization settings), which of the following viruses would be the simplest virus capable of completing its infectious cycle?
    • A) A virus that would consist of its nucleic acid and its capsid
    • B) A virus that would consist of its nucleic acid, its corresponding polymerase and its capsid
    • C) A virus that would consist of its nucleic acid, its corresponding polymerase, its capsid and its envelope
    • D) A virus that would consist of its nucleic acid, its corresponding polymerase, its capsid, its matrix and its envelope
    • E) A virus that would consist of its nucleic acid, its corresponding polymerase, its capsid, its matrix, its tegument and its envelope
  142. Viral replication proceeds as follows:
    • A) Attachment-Entry-Uncoating-Genome replication-Assembly-Release-Maturation
    • B) Attachment-Entry-Genome replication-Uncoating-Assembly-Release-Maturation
    • C) Attachment-Entry-Uncoating-Genome replication-Release-Assembly-Maturation
    • D) Attachment-Uncoating-Entry-Genome replication-Assembly-Release-Maturation
    • E) Attachment-Entry-Uncoating-Assembly-Genome replication-Release-Maturation
  143. Maraviroc is a recently FDA (Food and Drug Administration) approved chemokine receptor antagonist that binds to human chemokine receptor CCR5. Given the function of CCR5 in the replication cycle of human immunodeficiency virus type 1 (HIV-1), which event is affected by this drug?
    • A) HIV-1 attachment to the cell
    • B) HIV-1 entry into the cell
    • C) HIV-1 uncoating
    • D) HIV-1 release from the cell
    • E) HIV-1 maturation
  144. The national regulatory body overseeing the transport of biohazard material in your country has asked you to provide an expert opinion concerning the safety level of an engineered composite virus that needs to be shipped from one laboratory to another. The virion in question possesses a capsid derived from HPV (Human Papilloma Virus) that contains rhinovirus (+) ssRNA and HAV (Hepatitis A Virus) RNA-dependent RNA polymerase. The nucleocapsid is surrounded with an envelope containing Ebola virus GP peplomer spikes. If this virion were to infect permissive cells, which kind of virus would be generated?
    • A) A human papillomavirus
    • B) A rhinovirus
    • C) A hepatitis A virus
    • D) An Ebola virus
    • E) A papirhinohepbolavirus
  145. In the previous example, which virion component would intervene in cell susceptibility?
    • A) The HPV capsid protein
    • B) The rhinovirus RNA
    • C) The RNA-dependent RNA polymerase
    • D) The GP peplomer spikes
    • E) None of the above
  146. Virulence factors play an important role in the pathogenesis of viral infections and include gene products (1) that alter viral replication, (2) that alter host defense mechanisms, (3) that facilitate viral spread, and (4) that are toxic to the host. Which of the following mechanisms generally favours viral spread?
    • A) Apoptosis
    • B) Autophagy
    • C) Virokines
    • D) Viroceptors
    • E) Antigenic drift
  147. Virulence factors play an important role in the pathogenesis of viral infections and include gene products (1) that alter viral replication, (2) that alter host defense mechanisms, (3) that facilitate viral spread, and (4) that are toxic to the host. Which of the following mechanisms favours viral replication?
    • A) Apoptosis.
    • B) Virally-encoded proteins that increase cell cycling.
    • C) Virokines.
    • D) Viroceptors.
    • E) The tandem action of the double-stranded RNA (dsRNA) binding proteins 2’-5’-oligo(A) synthetase and RNase L.
  148. Virulence factors play an important role in the pathogenesis of viral infections, and some of these factors alter host defence mechanisms. One such factor is the HCMV (human cytomegalovirus) US6 protein that inhibits TAP proteins (transporters associated with antigen processing). By inhibiting TAP, which host defence mechanism is affected by US6?
    • A) B-cell-mediated antigen presentation to naïve CD4+ cells
    • B) CD4+-mediated B-cell activation
    • C) Dendritic cell-mediated antigen presentation to naïve CD4+ cells
    • D) Somatic cell-mediated antigen presentation to activated CD8+ cells
    • E) CD4+-mediated CD8+ cell activation
  149. Virulence factors play an important role in the pathogenesis of viral infections. Such virulence factors include gene products that (1) alter viral replication, (2) host defence mechanisms, (3) facilitate viral spread, and (4) are toxic to the host. Which of the following virulence factors alters host immune defence mechanisms?
    • A) Human cytomegalovirus viroceptor expression
    • B) Rotavirus nsP4 protein expression
    • C) Influenza virus HA (hemagglutinin) protein expression
    • D) Human immunodeficiency virus-1 TM protein expression
    • E) Human immunodeficiency virus-1 reverse transcriptase proof-reading
  150. The hallmarks of antiviral immunity are type-I IFN-dependent defense mechanisms (IFN- and IFN-) and CD8+ T lymphocyte cytotoxicity (CTL). The CD8+ T lymphocyte cytotoxicity response is orchestrated by which of these cell types?
    • A) Natural Killer cells (NK cells)
    • B) Macrophages
    • C) CD4+ Thelper1 lymphocytes
    • D) CD4+ Thelper2 lymphocytes
    • E) B-lymphocytes
  151. As a means of virulence, some viruses down-modulate class I major histocompatibility complex (MHC-I) cell surface expression of the cells they infect, thereby sharply diminishing CD8+ T lymphocyte-mediated cytoxicity efficiency. Yet, viral populations can still be kept in check despite the lack of CD8+ T lymphocytes-mediated cytotoxicity. Which of the following cells are the most likely to be responsible for killing infected cells that express very low levels of MHC-I?
    • A) Natural Killer cells (NK cells)
    • B) Macrophages
    • C) Dendritic cells
    • D) Neutrophils
    • E) B-lymphocytes
  152. Why is class I-restricted major histocompatibility complex (MHC-I) antigen presentation so important for viral clearance?
    • A) Because MHC-I restricted antigen presentation is the first step in the production of neutralizing antibodies
    • B) Because MHC-I restricted antigen presentation is the first step in the activation of both Thelper1 and Thelper2 responses
    • C) Because MHC-I restricted antigen presentation is the main pathway through which virus-infected cells are killed
    • D) Because MHC-I restricted antigen presentation is the main pathway of antibody-dependent cell-mediated cytotoxicity (ADCC)
    • E) Because MHC-I restricted antigen presentation is required for B-cell clonal expansion
  153. Viral cell transformation can result from (1) the insertion of viral oncogenes into host cell genomes, (2) the integration of proviruses into host cell genomes near proto-oncogene regulatory sequences, (3) the permanent activation by viruses of host cell signalling pathways, and (4) the alteration of host cell cycling regulation by viruses. Which viruses are responsible for cell transformation due to integration of proviruses in the vicinity of proto-oncogenes (nontransducing viruses)?
    • A) Adenoviruses
    • B) Hepadnaviruses (Hepatitis B Virus)
    • C) Papillomaviruses
    • D) Herpesviruses
    • E) Retroviruses
  154. Trypanosoma brucei gambiense and T. b. rhodesiense, both responsible for African sleeping sickness, express pre-programmed VSG (Variant Surface Glycoproteins) molecule sequences on their surface. This mechanism allows these trypanosomes to avoid immune clearance by
    • A) having a fraction of the infecting population switching their surface coat in order to escape the immune response mounted by the host.
    • B) having a mixed population of infecting variants so that the host cannot mount an efficient immune response to all variants at one time.
    • C) having variants that differ in time so that infection with one variant does not confer immunity to the previously encountered variants.
  155. How does acyclovir slow down Herpesviridae replication?
    • A) By inhibiting viral protein synthesis
    • B) By inhibiting viral mRNA transcription
    • C) By inhibiting viral DNA replication
    • D) By inhibiting viral RNA replication
  156. How does ganciclovir slow down HCMV replication?
    • A) By inhibiting viral protein synthesis
    • B) By inhibiting viral mRNA transcription
    • C) By inhibiting viral DNA replication
    • D) By inhibiting viral RNA replication
  157. Virus shedding during acute EBV infection can be diminished by using acyclovir, a nucleoside analogue. Which polymerase would be inhibited by acyclovir?
    • A) RNA-dependent RNA polymerase
    • B) RNA-dependent DNA polymerase
    • C) DNA-dependent RNA polymerase
    • D) DNA-dependent DNA polymerase
    • E) Reverse transcriptase
  158. Ototoxicity and nephrotoxicity associated with this antibiotic:
    • a) cefotaxime (Claforan)
    • b) amikacin (Amikin)
    • c) aztreonam (Azactan)
    • d) ceftriaxone (Rocephin)
  159. Antibiotic's clearance from the body most likely influenced by severe hepatic disease:
    • a) penicillins
    • b) clindamycin (Cleocin)
    • c) rifampin (Rimactane)
    • d) B & C
  160. A sixty-year old male was recovering from bowel resection. The initial recovery period was unremarkable. Late on the third post-operative day the patient began hyperventilating with respiratory alkalosis. On the fourth post-operative day, the patient's condition rapidly worsened with a significant elevation of temperature (104.9 F), profound hypotension (65/38 mm Hg) and tachycardia. Urine output was very low with BUN and serum creatinine (5 mg%, which had increased from normal levels at admission) were elevated. . Gram staining of sputum, which was purulent, indicated gram-negative rods. WBC was 17000/mmseptic shock with a shift to the left. The diagnosis was fulminant bacteremia and septic shock. What mechanism is most likely responsible for this patient's tachycardia?
    • a) Direct effects of bacterial endotoxins on the SA node
    • b) Significant hypotension associated with low systemic vascular resistance.
    • c) Bacterial endotoxins bind to muscarinic cholinergic receptors, thus removing the dominating cholinergic tone in the heart.
    • d) Patient anxiety
  161. FALSE statement about penicillin G
    • a) Treatment of choice for viridans group streptococcal endocarditis.
    • b) Pen G and Pen V are the two natural penicillins.
    • c) Pen G can be combined with procaine, extending drug half-life
    • d) Pen G most effective when given orally
  162. A 92 year-old female was brought to the emergency room following an episode of low blood pressure and disorientation at the nursing home. She had been refusing food and drank little. She was provided i.v glucose and was rehydrated. Over the next few days her condition worsened with increasing periods of incoherence. She exhibited hyperventilation with respiratory alkalosis and pulmonary congestion. Her body temperature was slightly subnormal and she was hypotensive (75/40 mm Hg) and tachycardic. Her pulmonary congestion worsened as did her blood gases. Digoxin was administered. Blood cultures indicated the present of E. coli, leading to a definitive diagnosis of E. coli septicemia. Which drug(s) would be appropriate to treat the septicemia?
    • a) cefotaxime (Claforan)
    • b) ceftriaxone (Rocephin)
    • c) aztreonam (Azactan)
    • d) all of the above
  163. Antimicrobial treatment of this severely immune-depressed patient should not be initiated before
    • (A) The pathogen has been identified by the microbiology laboratory
    • (B) Specimens have been taken for laboratory tests and examinations
    • (C) The results of a Gram stain are available
    • (D) Antipyretic drugs have been given to reduce body temperature
    • (E) The results of antibacterial drug susceptibility tests are available
  164. If gentamicin is used systemically in the treatment of this patient, monitoring of serum drug level may be advised because
    • (A) The drug is unstable in gastric acid
    • (B) The antibacterial action is antagonized by beta-lactam antibiotics
    • (C) Gentamicin is hematotoxic
    • (D) The drug does not readily penetrate into the cerebrospinal fluid
    • (E) Gentamicin has a narrow therapeutic window
  165. A combination of drugs might be given to this pa­tient to provide coverage against multiple organ­isms or to obtain a synergistic action. Examples of antimicrobial drug synergism established at the clinical level do not include
    • (A) Amphotericin B and flucytosine in cryptococ-cal meningitis
    • (B) Carbenicillin and gentamicin in pseudomonal infections
    • (C) Penicillin and tetracycline in bacterial menin­gitis
    • (D) Rifampin and vancomycin in enterococcal infections
    • (E) Trimethoprim and sulfamethoxazole in coliform infections
  166. Assuming that the physician is concerned about the effects of renal impairment on drug dosage in this patient, which of the following drugs is LEAST likely to require dosage reduction in renal dysfunction?
    • (A) Amikacin
    • (B) Ciprofloxacin
    • (C) Clindamycin
    • (D) Trimethoprim-sulfamethoxazole
    • (E) Vancomycin
  167. Which of the following antibacterial agents ap­pears to be quite safe for the treatment of infec­tions in the pregnant patient?
    • (A) Azithromycin
    • (B) Clarithromycin
    • (C) Erythromycin
    • (D) Sulfadiazine
    • (E) Tetracycline
  168. A common drug interaction that occurs with the use of antimicrobial drugs, particularly drugs that have a wide antibacterial spectrum of activity, is
    • (A) Disulfiram-like reactions when ethanol is ingested
    • (B) Increased ototoxicity if administered to a patient on furosemide
    • (C) Enhancement of the anticoagulant effects of warfarin
    • (D) Increased adverse effects if acetaminophen is administered as an antipyretic
    • (E) Hypertension with ingestion of red wine and cheese
  169. There is no evidence that antimicrobial prophy­laxis is of established benefit in
    • (A) Contacts of the index case in mycoplasmal pneumonia
    • (B) "Traveler's diarrhea"
    • (C) Contacts of the index case in gonorrhea
    • (D) Recurrent urinary tract infection
    • (E) Tuberculin convenors
  170. All of the following drugs are anticipated to be of value in a bioterrorist attack that utilizes anthrax EXCEPT
    • (A) Cefazolin
    • (B) Ciprofloxacin
    • (C) Clindamycin
    • (D) Doxycycline
    • (E) Rifampin
  171. A 48-year-old patient is scheduled for a vaginal hysterectomy. An antimicrobial drug will be used for prophylaxis against postoperative infection. It is pro­posed that cefazolin, a first-generation cephalosporin, be given intravenously at the normal therapeutic dose immediately before surgery and continued until the pa­tient is released from the hospital. Which of the following statements about the pro­posed drug management of this patient is LEAST accurate?
    • (A) Without prophylaxis, the infection rate fol­lowing this procedure exceeds 5% under opti­mal conditions
    • (B) This drug will not be effective against anaerobes
    • (C) Probable pathogens do not become rapidly resistant to this drug
    • (D) Nosocomial (hospital-acquired) infection will be prevented by treatment throughout the period of hospitalization
    • (E) Prophylaxis has documented efficacy in this type of surgical procedure
  172. If the patient had been scheduled for elective colonic surgery, optimal prophylaxis against infec­tion would be achieved by mechanical bowel preparation and the use of
    • (A) Intravenous cefotetan
    • (B) Oral ampicillin
    • (C) Oral neomycin and erythromycin
    • (D) Intravenous third-generation cephalosporin
    • (E) Oral fluoroquinolone
  173. Which of the following antimicrobial drugs is LEAST likely to affect the hepatic metabolism of other drugs?
    • (A) Ampicillin
    • (B) Clarithromycin
    • (C) Erythromycin
    • (D) Ketoconazole
    • (E) Rifampin
  174. Which of the following antimicrobial drugs does not require supplementation of dosage following hemodialysis?
    • (A) Ampicillin
    • (B) Cefazolin
    • (C) Ganciclovir
    • (D) Tobramycin
    • (E) Vancomycin
  175. The persistent suppression of bacterial growth that may occur after limited exposure to some antimi­crobial drugs is called
    • (A) Time-dependent killing
    • (B) The postantibiotic effect
    • (C) Clinical synergy
    • (D) Concentration-dependent killing
    • (E) Sequential blockade
  176. If ampicillin and piperacillin are used in combina­tion in the treatment of infections resulting from Pseudomonas aeruginosa, antagonism may occur. The most likely explanation is that
    • (A) The 2 drugs form an insoluble complex
    • (B) Piperacillin blocks the attachment of ampi­cillin to penicillin-binding proteins
    • (C) Ampicillin induces beta-lactamase production
    • (D) Autolytic enzymes are inhibited by piperacillin
    • (E) Ampicillin is bacteriostatic

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