Microbiology Exam VI: Transfusion Transmitted Diseases, Bioterrorism, Campylobacter and Anaerobes

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Microbiology Exam VI: Transfusion Transmitted Diseases, Bioterrorism, Campylobacter and Anaerobes
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2013-05-06 18:00:31
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Microbiology Transfusion Transmitted Diseases Bioterrorism Campylobacter Anaerobes
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Microbiology Exam VI: Transfusion Transmitted Diseases, Bioterrorism, Campylobacter and Anaerobes
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  1. Name the viruses implicated in transfusion infections:
    • 1. HIV
    • 2. Hepatitis C, B, and G
    • 3. West Nile Virus
    • 4. HTLV-1 and 2
    • 5. CMV
    • 6. EBV
    • 7. Cold-related viruses
  2. What organisms other than viruses are implicated in transfusion infections?
    • 1. Bacterial
    • 2. Parasites
    • 3. Prions (Creutzfeldt-Jakob)
  3. What is the most common case of contamination of blood products?
    Bacteria
  4. Which blood product is most prone to contamination?
    Platelets
  5. When does contamination usually occur?
    During blood draw.
  6. When does overgrowth typically occur in blood product?
    When incubated outside of donor away from host's immune system.
  7. When do signs and symptoms usually occur from bacterial contamination of blood products?
    Usually during transfusion with some reports of delayed transfusion reactions.
  8. What are the signs and symptoms from bacterial contamination of blood products?
    Fever, chills, hypotension, shock, nausea and vomiting.
  9. What are the clinical complications due to the bacterial contamination of blood products?
    DIC, hypotensive shock, renal failure and death.
  10. WHat are risk factors that contribute to a high rate of fatality regarding bacterial contamination of blood products?
    • 1. type of component
    • 2. identity and amount of organism
    • 3. patient's age
    • 4. amount transfused
  11. What component is the worst when implicated in the high rate of fatalities involving contaminated blood products?
    platelets
  12. What is the worst organism to have in the bacterial contamination of blood components?
    Gram negatives—Pseudomonas
  13. What patient demographic is the most at risk for the high rate of fatalities involving contaminated blood products?
    the elderly
  14. What is always the first step during a transfusion reaction?
    Stop transfusion
  15. What organisms are common contaminates of RBC blood components?
    • 1. Pseudomonas
    • 2. Acinetobacter
    • 3. Yersinia
    • 4. E. coli
    • 5. Staph aureus Coag neg
  16. What organisms are common contaminates of platelets?
    • 1. Staph
    • 2. Acinetobacter
    • 3. Klebsiella
    • 4. E. coli
    • 5. Strep
    • 6. Salmonella
    • 7. Serratia
  17. What steps are taken if a reaction occurs and contamination is suspected during transfusion?
    • 1. Stop the transfusion
    • 2. gram stain the contents of the bag
    • 3. examine the bag
    • 4. culture the bag
    • 5. collect bags of all units transfused
  18. What is the value of culturing a contaminated unit after a transfusion if it is too late to administer treatment?
    It may aid in identifying other units that may be contaminated by the same donor so that they may be pulled.
  19. What supportive treatment is administered to patients who received contaminated blood products?
    Fluids and respiratory aid.
  20. What antibiotic treatment is administered to patients who received contaminated blood products?
    Beta-lactam and aminoglycosides, usually given before culture starts.
  21. What methods are employed to limit contamination of blood products?
    • 1. Platelet concentrates are inspected and kept on constant swirling
    • 2. Oxygen consumption is measured
  22. What are the two main testing modalities for viruses?
    • 1. Serology - looks for antibodies and antigens
    • 2. Nucleic Acid Testing (NAT) - looks for nucleic acids and genomes
  23. What is the advantage of NAT vs Serology?
    • 1. NAT is not susceptible to a window period of testing preventing false negatives, and is more sensitive than serology
    • 2. Serology is inexpensive compared to NAT
  24. What is the incidence of HIV transmitted by transfusion?
    Less than 1 per 1,000,000 transfusions
  25. WHat testing is used to prevent false negatives in the window period of HIV?
    NAT testing (Nucleic Acid Testing)
  26. What transmitted disease reported a large number of infections in the early days due to transfusions, which are now reported  at less than 1 per 1,000,000?
    HIV
  27. What disease has a very low incidence of transmission by transfusion, where donors are tested for its surface antigen and core antibodies?
    Hepatitis B
  28. What is the hallmark of HBV infections?
    • 1. Appears 1 to 10 weeks after viremia starts
    • 2. Disappears after recovery of acute phase
  29. What is the only marker that is still seen in the window period between disappearance of sAg (surface antigen) during and HBV infection?
    HBc IgM (Hepatitis B core antibody)
  30. What HBV marker appears late and persists for life?
    HBc IgG (Hepatitis core antibody)
  31. What fairly rare pathogen needs HCV to become pathologically active?
    HGV
  32. What pathogen has a very low rate of transfusion related transmission and tested through serology and NAT?
    HCV
  33. What strain of Hepatitis has low morbidity and mortality upon transmission, and requires active viremia or immunocompromised recipient to cause infection?
    Hep A
  34. How can you differentiate an acute Hep A infection versus a past infection?
    • Serology: IgM indicates acute
    • IgG indicates past
  35. This pathogen is characterized as a ssRNA retrovirus, causes T-cell leukemia and lymphoma, and is highly associated with IV drug abuse:
    HTLV-I and II
  36. How would you test for HTLV-I and II?
    NAT testing (nucleic acid test)
  37. What is the main route of infection of the West Nile Virus?
    Mosquitoes
  38. What ssRNA virus is transmitted during West Nile Virus infections? What is the main route of infection?
    • 1. Flavivirus
    • 2. Mosquitoes
  39. How is the West Nile Virus tested for?
    NAT testing (nucleic acid)
  40. What other transmission routes of the West Nile Virus were discovered in 2002 by the CDC?
    • 1. Blood products
    • 2. Organ transplants
    • 3. Breast milk
  41. How is CMV eliminated in blood products?
    Leukoreduction
  42. When is CMV an issue in the transfusion of blood products?
    The immunocompromised and low-birth weight neonates.
  43. How is EBV treated for during the transfusion of blood products?
    EBV is not tested for and there are few reports of transmission by transfusion.
  44. What infections are not routinely tested for but screened by for by history of travel?
    • 1. CJD (Creutzfeldt-Jakob Disease)
    • 2. Chagas
    • 3. Babesiosis
  45. What is the most important measure to prevent the transmission of pathological agents in blood transfusions?
    The screening of donors and donor selection.
  46. What are grounds for indefinite deferral when screening donor units?
    • 1. Viral hepatitis after 11 years of age
    • 2. Positive HBsAg or repeated HBclg
    • 3. Any evidence of HIV or HTLV
    • 4. Chagas or Babesiosis
    • 5. Stigma of parental or IV drug use
    • 6. Injection of any non-prescriton drugs
    • 6. Risk of CJD
  47. What are the conditions for a 12 month deferral  when screening donors?
    • 1. mucous membrane exposed to blood.
    • 2. sexual contact with a confirmed positive individual or high risk individual (prostitute, IV drug users).
    • 3. Incarceration at a correctional facility => 72hrs
    • 4. History of syphilis or gonorrhea
    • 5. Tattos
  48. What are the conditions for deferral  when screening donors for Malaria?
    • 1. Defer during symptomatic infection
    • 2. Allow after 3 years without symptoms
    • 3. Consider deferral after travel to endemic areas
  49. When can deferred donors be readmitted into the random donor pool?
    • 1. If not on permanent deferment
    • 2. A specific period of time has passed between results
    • 3. The samples come back repeatedly negative on different assays with multiple lot numbers.
  50. True or False. Infectious reactions and transmission due to transfusions are exceedingly rare.
    True
  51. What is the best way to prevent the transmission of pathogens in transfusions?
    Screen donors
  52. True or False. Random donor pool is not as safe as directed donor pool.
    False. Random and direct are both safe.
  53. Which transfusion infection is implicated in acute GI complication?
    Hepatitis A
  54. In Hepatitis B infections, which is the major marker and what is done if it is present in regards to the transfusion blood components?
    • 1. The surface antigen is the major marker in Hep B
    • 2. If the surface antigen is present, blood will be removed from available donor pool
  55. What do you do if a patient is having a fever due to transfusion?
    Stop the transfusion immediately and differentiate febrile reaction from other reactions
  56. What type of organism requires O2 as its final electron acceptor?
    Obligate aerobe
  57. What type of organism requires decreased O2 tension?
    microaerophilic
  58. What type of organism is characterized by growing equally well with or without oxygen, representing most pathogens?
    Facultative anaerobe
  59. What type of organism grows poorly in O2?
    aerotolerant
  60. What type of organism toxically affected by O2?
    Obligate anaerobe
  61. When is an endogenous strain (normal flora) pathogenic?
    When they gain access to normally sterile sites.
  62. How do endogenous organisms (normal flora) gain access to normally sterile sites?
    Surgery or trauma, or if normal defense mechanisms are compromised via malignancy, immunosuppressive therapy, or diabetes.
  63. What are examples of common exogenous pathogens and what do they cause?
    • Clostridium tetani - tetanus
    • Clostridium perfringes - gas gangrene
    • Clostridium botulinum - botulism
  64. How do exogenous pathogens gain access to the body?
    Through existing wounds or by puncture with objects contaminated  with toxigenic Clostridium species.
  65. Besides wounds or puncture, what are additional modes of acquisition of Clostridium?
    • 1. Ingestion of preformed toxins in foods - Botulism, C. perfringes
    • 2. GI colonization with toxin-producing organisms - infant botulism
    • 3. Person-to-pesron nosocomial spread of C. diff and bite wounds
  66. Why are swabs a poor alternative to the collection and transport of organisms? What is the best method of collection?
    • 1. Swabs can lead to excessive drying, easier contamination, and retention of organisms in the fibers.
    • 2. Tissue biopsies or aspiration using a needle and syringe.
  67. How are all anaerobic cultures plated (at RGH)?
    BAP, anaerobic Columbia, and Laked Kanamycin/Vancomycin Blood Agar.
  68. What two mediums used to culture anaerobes are incubated in anaerobe jars or pouches?
    Columbia and LKV
  69. What condition must be met if anaerobic specimens are to be processed on open bench-tops?
    Specimens must be incubated immediately thereafter, in anaerobic jars, pouches, or performed in an anaerobic chamber.
  70. What is a "holding jar" used for during anaerobic work ups?
    A temporary holding container for anaerobic work ups, using N2 instead of CO2 that reacts with water to produce carbonic acid, thus promoting an anaerobic environment.
  71. How many plates can anaerobic jars and plates hold?
    Jars = 15, pouches = 5
  72. True or False. Both anaerobic jar and pouches use a hydrogen and CO2 generating system.
    True
  73. What characteristics are observed during examination of cultures?
    Colony morphology, fluorescence, pigmentation, gram stain, and aerotolerance
  74. What medium and conditions are used for aerotolerance testing?
    Each colony type is subbed to a Choc in CO2 and BAP incubated anaerobically.
  75. What are the classical biochemicals used in the identification of anaerobic cultures?
    • 1. growth in Bile
    • 2. spot indole
    • 3. catalase
  76. What antibiotics are used in the identification of anaerobes?
    • 1. Kanamycin
    • 2. Vancomycin
    • 3. Colistin
  77. What are methods used in the Identification of anaerobes?
    • 1. Biochem - Bile, indole, catalase
    • 2. ID Discs - Kanamycin, Vancomycin, Colistin
    • 3. Commercial ID Systems
    • 4. Gas Liquid Chromatography (time consuming, impractical)
  78. When is susceptibility testing warranted for anaerobes?
    When an infection is caused by a single anaerobe. However if multiple organisms are identified, testing will not be performed.
  79. True or False. Most clinically relevant anaerobes are not susceptible to first-line antimicrobials.
    False.
  80. What susceptibility testing is performed on anaerobes?
    • Beta-lactamase
    • E-test
    • Agar dilution MIC
  81. When is beta-lactamase testing on anaerobes accurate?
    Only when done anaerobically.
  82. True or False. Most anaerobic gram negative rods are positive during beta-lacatamse testing.
    True
  83. What is the general treatment for anaerobic infections?
    Clindamycin, metranidazole, and 3rd generation cephalosporins
  84. How is an agar dilution MIC performed?
    Use pre-reduced anaerobically sterilized media and run multiple organisms at once.
  85. What is the biggest factor when dealing with anaerobic infections?
    Time. After culture, have to prove organism is an anaerobe and do testing. By then, the patient would have already been treated.
  86. What are two kinds of commercial kits available for anaerobic identification?
    • 1. API
    • 2. use of preformed enzymes
  87. What non-selective media is used in the detection of anaerobes?
    Columbia agar. Used for anaerobes and facultative.
  88. What selective media is used in the detection of anaerobes?
    LKV. Selective for Prevotella and Bacteroides
  89. What is Laked Blood?
    Laked blood media is hemolyzed blood.
  90. Besides O2, what are anaerobes sensitive to?
    Carbonic acid
  91. An aspirate of a deep wound was plated on blood agar plates and incubated aerobically and anaerobically. At 24 hours there was growth on both plates. This indicates that the organism is a(n):

    A. nonfermenter
    B. aerobe
    C. facultative anaerobe
    D. obligate anaerobe
    C. facultative anaerobe
    (this multiple choice question has been scrambled)
  92. In order to isolate Campylobacter coli/jejuni, the fecal specimen should be:

    A. inoculated into selective plating media and incubated in reduced oxygen with added CO2 at 42C
    B. stored in tryptic soy broth before plating to ensure growth of the organism
    C. inoculated into selective plating media and incubated at both 35C and at room temperature
    D. incubated at 35C for 2 hours in Cary-Blair media before inoculating onto selective plating media
    A. inoculated into selective plating media and incubated in reduced oxygen with added CO2 at 42C
    (this multiple choice question has been scrambled)
  93. The most common cause for failure of a GasPak anaerobic jar to establish an adequate environment for anaerobic incubation is:

    A. catalyst that have become inactivated after repeated use
    B. condensation of water on the inner surface off the jar
    C. the failure of the oxidation-reduction potential indicator system due to deterioration of methylene blue
    D. the failure of the packet to generate adequate H2 and/or CO2
    A. catalyst that have become inactivated after repeated use
    (this multiple choice question has been scrambled)
  94. Which of the following groups of specimens would be acceptable for anaerobic culture?

    A. vaginal, eye
    B. ear, leg tissue
    C. pleural fluid, brain abscess
    D. urine, sputum
    C. pleural fluid, brain abscess
    (this multiple choice question has been scrambled)
  95. Which of the following is the most appropriate organism and media combination?

    A. Campylobacter species—charcoal yeast extcract
    B. Legionella species—Regan Lowe
    C. Clostridium difficile—phenylethyl alcohol (PEA)
    D. Yersinia enterocolitica—cefsulodin-igrasin-novobiocin (CIN)
    D. Yersinia enterocolitica—cefsulodin-igrasin-novobiocin (CIN)
    (this multiple choice question has been scrambled)
  96. A gram stain from a swab of a hand wound reveals:

    moderate neutrophils
    no squamous epithelial cells
    moderate gram-positive cocci in chains
    moderate large gram-negative bacilli

    Select the appropriate media that will selectively isolate each organism.

    A. sheep blood, MacConkey
    B. Columbia CNA, MacConkey
    C. KV-Laked agar, Thayer Martin
    D. Columbia CNA, chocolate
    B. Columbia CNA, MacConkey

    CNA will select for gram positives and MacConkey will select for gram negs.
    (this multiple choice question has been scrambled)
  97. Which of the following must be incubated in a microaerophilic environment for optimal recovery of the organism?

    A. Pseudomonas aeruginosa
    B. Campylobacter jejuni
    C. Escherichia coli
    D. Proteus mirabilus
    B. Campylobacter jejuni
    (this multiple choice question has been scrambled)
  98. Which of the following media can be used to culture Campylobacter jejuni?

    A. bismuth sulfate
    B. anaerobic CNA agar
    C. Skirrow medium
    D. CIN agar
    C. Skirrow medium
    (this multiple choice question has been scrambled)
  99. The optimal wound specimen for culture of anaerobic organisms should be:

    A. a swab of lesion obtained after administration of antibiotics
    B. a swab of lesion obtained before administration of antibiotics
    C. a syringe filled with pus, obtained after administration of antibiotics
    D. a syringe filled with pus, obtained before administration of antibiotics
    D. a syringe filled with pus, obtained before administration of antibiotics
    (this multiple choice question has been scrambled)
  100. A 21-year-old patient presents with pharyngitis. A throat swab is collected and submitted fro anaerobic culture. This specimen should be:

    A. set up immediately
    B. inoculated into thioglycolate broth
    C. rejected as unacceptable
    D. sent to a reference laboratory
    C. rejected as unacceptable

    Anaerobes do not cause pharyngitis. Most common cause is strep.
    (this multiple choice question has been scrambled)
  101. Anaerobic susceptibility testing is helpful in the management of patients with:

    A. pilonidal sinuses
    B. rectal abscesses
    C. synovial infections
    D. streptococcal pharyngitis
    C. synovial infections

    Normally sterile site.
    (this multiple choice question has been scrambled)
  102. What is the morphology and gram stain of the most commonly encountered anaerobic bacteria in clinical infections?
    Gram negative anaerobic rods
  103. Where in the body are gram negative anaerobic bacteria considered normal flora?
    Mouth, upper respiratory tract, intestinal tract, and urogenital tract.
  104. How can anaerobic bacteria be differentiated from facultative anaerobes?
    By anaerobes inability to grow in the presence of oxygen and their susceptibility to matronizadole
  105. What is the most commonly encountered anaerobe in infections?
    Bacteroides fragilis
  106. What anaerobe is recovered from most intra -abdominal abscesses, and is the dominant normal colon flora?
    Bacteroides fragilis
  107. What are the two most important species of Bacteroides?
    B. fragilis and B. thetaiomicron
  108. What are characteristics of the Bacteroides fragilis group?
    • 1. Bile resistant
    • 2. more antibiotic resistance than other anaerobes
    • 3. non-sporeformer
    • 4. found in colon and female genital tract

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