Microbiology Exam #3

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Microbiology Exam #3
2014-04-04 10:58:05

Microbiology Exam #3
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  1. Pathology & Epidemiology
    • Pathology = the study of disease
    • Epidemiology = the study of the spread of disease
  2. Etiology, Pathogenisis, Infection, Disease
    • Etiology = the study of the cause of disease
    • Pathogenisis = the development of disease
    • Infection = colonization of the body by pathogens
    • Disease = an abnormal state in which the body is not functioning normally
  3. Competitive Exclusion
    • Normal flora protect the host by:
    • Occupying niches that pathogens might occupy
    • Producing acids
    • Producing bacteriocins
  4. Symbiosis
    • Commensalism = one organism benefits & the other is unaffected
    • Mutualism = both organisms benefit
    • Parasitism = one organism benefits at the expense of the other
  5. Probiotics
    Live microbes applied to or ingested into the body, intended to exert a beneficial state
  6. Kochs' Postulates
    • Used to prove the cause of an infection
    • Same pathogen must be present in every case of the disease
    • Pathogen must be isolated from the disease's host & grown in pure culture
    • Pathogen from the pure culture must cause the disease when inoculated into a healthy susceptible lab animal
    • Pathogen must be isolated from the inoculated animal & must be shown to be the original pathogen
  7. Classification of Diseases
    • Communicable Disease = spread from 1 host to another
    • Contagious Disease = easily spread from 1 host to another
    • Noncommunicable Disease = not transmitted from 1 host to another
    • Endemic = constantly present in a population
    • Epidemic = acquired by many in a given area in a short period
    • Sporadic = occurs occasionally in a population
    • Acute = symptoms develop rapidly
    • Chronic = develops slowly
    • Subacute = symptoms between acute & chronic
    • Latent = disease with a period of symptoms when the causative agent is inactive
    • Local Infection = pathogens are limited to a small area of the body
    • Systemic Infection = an infection throughout the body
    • Primary Infection = acute infection causing initial illness
    • Secondary Infection = occurs after host is weakened by primary infection
  8. Symptom, Sign, Syndrome
    • Symptom = a change in body function that is felt by a patient
    • Sign = a change in a body that can be measured or observed
    • Syndrome = a specific group of signs & symptoms that accompany a disease
  9. Incidence & Prevalence
    • Incidence = fraction of a population that contracts the disease during a specific time - # of new cases
    • Prevalence = fraction of a population having a specific disease at a given time - total # of cases
  10. Stages Of Disease
    • 1.  Incubation Period = no signs or symptoms
    • 2.  Prodromal Period = mild signs or symptoms
    • 3.  Period of Illness = most severe symptoms
    • 4.  Period of Decline = some lingering signs
    • 5.  Period of Convalesence = recovery; no signs or symptoms

    Period of Illness & Period of Decline = highest # of microbes
  11. Disease Transmission
    • Reservoirs = continual sources of infection; human - AIDS; animal - rabies; nonliving - botulism
    • Transmission = contact - direct, indirect, or droplet; vehicle - transmission by an inanimate reservoir
    • Vectors = arthropods (fleas, ticks, mosquitos); transmit by mechanical or biological transmission
    • Nosocomial = acquired as a result of a hospital stay; due to compromised host; direct contact; fomites (catheters, breathing tubes, syringes)
  12. Pathogenicity & Virulence
    • Pathogenicity = the ability to cause disease
    • Virulence = the extent of pathogenicity
  13. Portals of Entry & Exit
    Portal of Entry = specific route by which a pathogen gains access to the body - done through mucous membranes (eye, respiratory tract, GI, urogenital tract), skin (can't penetrate skin but come in through hair follicles & ducts), and parenteral routes (bites, injections, wounds).

    Portal of Exit = respiratory tract (coughing & sneezing), GI tract (feces & saliva), genitourinary tract (urine & vaginal secretions), and blood (biting arthropods or syringes).
  14. LD50 Vs. ID50
    • LD50 = lethal dose (of a toxin) for 50% of a test population - dependent on type of toxin
    • ID50 = infectious dose for 50% of the test population - dependent on portal of entry
  15. Adherence
    • Adhesins/ligands are surface projections that bind to receptors on host cells
    • If ligand receptors are altered, then infection can be prevented or increased
    • Biofilms provide attachment & resistance to antimicrobial agents
  16. Mechanisms for Penetration of Host Defenses by Bacteria
    Capsules = prevent phagocytosis

    Cell Wall Components = M protein resists phagocytosis, opa protein inhibits T helper cells, & mycolic acid layer resists digestion


    Antigenic Variation = alter surface proteins

    Penetration Into Host Cell Cytoskeleton = invasins (ruffle membrane & enter) & uses actin to move from one cell to the next
  17. Mechanisms for Damaging Host Cells By Pathogens
    Using Host Nutrients = bacteria need iron to live but very little free iron is found in the body, so siderophores bind very tightly to Fe & remove it from host

    Direct Damage = host cells can be damaged or destroyed when pathogens metabolize & multiply inside the host which disrupts host cell function, produces waste products, & produces toxins
  18. Endotoxins Vs. Exotoxins
    Endotoxins = Gram -, located in outermembrane of cell wall, Lipopolysaccharide composition, systemic response (fever, decrease in blood pressure, endotoxic shock), diverse range of effects, 1 type, released during lysis or replication 

    Exotoxins = Gram +, located in cytoplasm, generally very potent, specific effects in host, 3 types (A-B, membrane disrupting, & superantigens), produced as part of growth & metabolism
  19. A-B Toxins
    Consist of active component that inhibits cell processes & a binding component that attaches the toxin to the cell
  20. Endotoxins
    • Released during lysis of bacteria or during replication
    • Cause release of immune factors resulting in high fever & shock
    • They can allow bacteria to cross the blood-brain barrier by increasing blood vessel leakiness
  21. Cytopathic Effects Caused By Viruses
    • Stop mitosis
    • Cell fusion
    • Cell lysis
    • Inclusion bodies
    • Antigenic & chromosomal changes
  22. Pathogenic Properties of Fungi
    • Fungal waste products may cause symptoms
    • Chronic infections provoke an allergic response
    • Capsules prevent phagocytosis
    • Ergot Toxin
    • Aflatoxin
    • Proteases
  23. Pathogenic Properties of Protozoa
    • Waste products may cause symptoms
    • Can avoid host defenses by growing in phagocytes
    • Antigenic variation
  24. Pathogenic Properties of Helminths
    • Use host tissue for growth
    • Presence of parasite interferes with host functions
    • Parasite's metabolic waste can cause symptoms
  25. Antibiotic
    Substance produced by a microbe that, in small amounts, inhibits other microbes
  26. Selective Toxicity
    Drug that kills harmful microbes without harming host
  27. Spectrum of Activity for Drugs
    • Broad = affect a diverse range of microbes
    • Narrow = affect only a specific group of microbes (gram +)
  28. 5 Major Modes of Action of Antimicrobial Drugs
    Inhibit Cell Wall Synthesis = penicillin - inhibits peptidoglycan synthesis leading to cell lysis; effective against gram + bacteria

    Inhibition of Protein Synthesis = Chloramphenicol binds 50s subunits which inhibits peptide bond formation; Aminoglycosides change the shape in the subunit; Tetracyclines bind to 30s subunits interfering with tRNA attachment to mRNA-ribosome complex; Streptogramins bind to 50s subunits & cause release of incomplete polypeptide; Macrolides bind to 50s & block the funnel of ribosomes preventing translation

    Plasma Membrane Disruption = Polymyxin B inhibits fatty acid synthesis

    Inhibition of Nucleic Acid Synthesis = Rifamycin inhibits RNA synthesis; Quinolones/Fluoroquinolones inhibit DNA gyrase

    Competitive Inhibitors = Sulfonamides inhibit folic acid synthesis & affect nucleic acid synthesis
  29. Natural Vs. Semi-Synthetic Penicillins
    • Natural = produced by penicilium & affective against gram + & spirochetes
    • Semi-Synthetic = made in lab, resistant to penicilinases & has a broader range of activity
  30. Antifungal Drugs
    Damage plasma membranes by inhibiting ergosterol synthesis & increasing membrane permeability allowing disruption
  31. 3 Types of Antiviral Drugs
    1.  Nucleoside & Nucleotide Analogs

    2.  Enzyme Inhibitors = inhibit attachment & uncoating

    3.  Interferons = produced by body to prevent viral spread; also have synthetic alpha interferons; Imiquimod is a drug that stimulates interferon production
  32. 2 Ways In Which Drugs Are Tested For Effectiveness
    1.  Disk Diffusion = AKA Kirby-Bauer Test; a drug soaked disc is placed on a lawn of microbes - look for zone of inhibition (MIC - minimal inhibitory concentration)

    2.  Broth Dilution = microbe is grown in a broth containing different concentration of the drug - lowest concentration of the drug that still kills is the MBC (minimal bacteriocidal concentration)
  33. 4 Mechanisms of Antibiotic Resistance
    • Enzyme destruction of drug
    • Prevention of penetration of drug
    • Alteration of drug's target site
    • Rapid ejection of the drug
  34. Gram - Sepsis
    Causative Agent = Endotoxin from gram - bacteria

    Identifying Characteristics = caused by endotoxin, drop in blood pressure (septic shock)
  35. Gram + Sepsis
    Causative Agent = Enterococcus, Group B Strep, S. aureus

    Identifying Characteristics = nosocomial
  36. Purperal Fever
    Causative Agent = Streptococcus pyogenes

    Identifying Characteristics = childbirth fever, handwashing prevents spread, Semmelweiss
  37. Bacterial Endocarditis
    Causative Agent = S. aureus mostly

    Identifying Characteristics = infection of endocardium, arises from focal infection usually from tooth extraction, rapid destruction of heart valves
  38. Rheumatic Fever
    Causative Agent = Streptococcal (Group A, hemolytic)

    Identifying Characteristics = autoimmune complication displaying as arthritis or heart inflammation, follows strep throat, anti-strep antibodies cross-react with heart tissue or with strep antigens in joints
  39. Tularemia
    Causative Agent = Francisella tularensis

    Identifying Characteristics = rabbit reservoir, ulcer at entry site, septicemia & pneumonia, possible bioterrorist agent
  40. Anthrax
    Causative Agent = Bacillus anthracis

    Identifying Characteristics = endospores cause infection, 3 types:  1.  cutaneous (most common) 2.  GI (moderate mortality) 3.  pulmonary (100% mortality), 2 toxins = edema & lethal toxin
  41. Gangrene
    Causative Agent = Clostridium perfringens

    Identifying Characteristics = soft tissue death due to lack of oxygen, susceptible to anaerobic bacteria, amputation recommended
  42. Plague
    Causative Agent = Yersinia pestis

    Identifying Characteristics = vector is rat flea, rats are reservoir, bubonic has bruises & buboes, pneumonic leads to pneumonia
  43. Relapsing Fever
    Causative Agent = Borellia sp.

    Identifying Characteristics = spirochete bacteria, transmitted by soft ticks, fever, jaundice, rose colored spots, recurs several times
  44. Lyme Disease
    Causative Agent = Borellia burgdorfer

    Identifying Characteristics = tick transmission, bulls eye rash, neurological symptoms
  45. Epidemic Typhus
    Causative Agent = Rickettsia prowazekii

    Identifying Characteristics = human body louse transmits in feces, prevalent in crowded unsanitary living conditions, rash, fever, stupor
  46. Rocky Mountain Spotted Fever
    Causative Agent = Rickettsia rickettsii

    Identifying Characteristics = tick found on spotted deer, rash looks like measles
  47. Burkitt's Lymphoma & Infectious Mononucleosis
    Causative Agent = EBV

    Identifying Characteristics = tumor on jaw, virus latent in immune cells causing tumor in immunosurpressed, mono is transmitted by saliva, causes proliferation of atypical lymphocytes & flue like symptoms
  48. Cytomegalovirus Infection
    Causative Agent = CMV

    Identifying Characteristics = cytomegaly (enlargement of cells), transmitted in body fluids, latent in immune cells, congenital issues if crosses the placenta
  49. Yellow Fever
    Causative Agent = Yellow Fever Virus

    Identifying Characteristics = fever, chills, headache, jaundice, no tx but vaccine available, transmitted by mosquito
  50. Dengue Hemorrhagic Fever
    Causative Agent = Dengue Fever Virus

    Identifying Characteristics = mosquito, fever, muscle joint pain, rash, can lead to shock
  51. Emerging Hemorrhagic Fevers
    Causative Agent = Ebola, Marburg, Lassa Fever; Hantavirus Viruses

    Identifying Characteristics = Ebola, Lassa:  filoviruses, disrupts clotting system causing massive internal bleeding & bleeding out, Hantaviurs:  inhalation of dried rodent feces (pulmonary syndrome)
  52. Chaga's Disease
    Causative Agent = Trypanosoma cruzi

    Identifying Characteristics = vector is kissing bug, intracellular parasite with undulating membrane, passed in feces when rubbed into bite site or eyes, acute fever then can result in mega colon due to damage in nerves controlling peristalsis
  53. Toxoplasmosis
    Causative Agent = Toxoplasma gondii

    Identifying Characteristics = sexual stage is in cats, humans get infected by meat or infected feces, cyst stage can occur in brain leading to damage & vision problems, immunocomprimised - AIDS, pregnancy
  54. Malaria
    Causative Agent = Plasmodium sp.

    Identifying Characteristics = chills, fever, headache at 2 - 3 day intervals, transmitted by mosquito, infect RBCs, control in nets
  55. Leishmaniasis
    Causative Agent = Leishmania sp.

    Identifying Characteristics = transmitted by sandflies, reproduce in liver, spleen, & kidneys, cutaneous with sore at bite site or visceral with organ enlargement & flue-like symptoms
  56. Schistosomiasis
    Causative Agent = Schistosoma sp.

    Identifying Characteristics = blood fluke, adults live in veins of liver & bladder, coat with host proteins to avoid detection, lead to heptosplenomegaly
  57. Swimmer's Itch
    Causative Agent = Cercaria of Schistomes

    Identifying Characteristics = free living stage of fluke, penetrate skin of humans & can cause allergic reaction in skin
  58. Streptococcal Pharyngitis (strep throat)
    Causative Agent = Group A Streptococci (Streptococcus pyogenes)

    Identifying Characteristics = inflammation of mucous membranes, fever, sometimes tonsillitis & ear infections
  59. Scarlet Fever
    Causative Agent = Erythrogenic-producing S. pyogenes (toxin production results from phage lysogeny)

    Identifying Characteristics = symptoms include a spotted strawberry appearance of tongue & a pinkish red rash due to toxin, tongue can swell & lose upper membrane
  60. Diptheria
    Causative Agent = Exotoxin-producing Corynebacterium diptheria (toxin results from phage lysogeny)

    Identifying Characteristics = exotoxin produces a membrane of fibrin & dead cells in the throat & can block air passage, exotoxin inhibits protein synthesis & can cause heart, kidney, or nerve damage, vaccine = DTaP
  61. Otitis Media
    Causative Agent = S. penumonia, S. pyogenes, Staph aureus, Hemophilus influenza, & others

    Identifying Characteristics = earache - complication of nose & throat infections, pus accumulation causes pressure on ear drums
  62. Pertussis (whooping cough)
    Causative Agent = Bordetella pertussis

    Identifying Characteristics = whooping sound occurs from gasping for air between cough, bacteria destroy ciliated cells in respiratory tract causing slowing of mucociliary escalator & accumulation of mucus in lungs, can be sever in children with violent coughing fits
  63. Tuberculosis
    Causative Agent = Mycobacterium tuberculosis

    Identifying Characteristics = acid fast bacteria, form lesions called tubercles with dead macrophages & bacteria, TB skin test can indicate past exposure or active case of TB, main symptom is coughing which can be blood-stained as tissues are damaged
  64. Pneumococcal pneumonia (typical pneumonia)
    Causative Agent = Streptococcus pneumonia

    Identifying Characteristics = encapsulated strains are virulent, symptoms include difficulty breathing, high fever, & chest pain with rust-colored sputum
  65. Legionellosis
    Causative Agent = Legionella pneumophila

    Identifying Characteristics = high fever, cough, & pneumonia-like symptoms, not transmitted between people, bacteria found in water & disseminated in air from air-conditioning cooling towers
  66. The Common Cold
    Causative Agent = 200 different viruses (rhinovirus accounts for 50% of all colds)

    Identifying Characteristics = sneezing, nasal secretions, & congestion
  67. Viral Pneumonia
    Causative Agent = Number of different viruses but Respiratory syncytial virus common in children

    Identifying Characteristics = RSV causes fusion of cells (syncytium) when grown in culture
  68. Influenza
    Causative Agent = Influenzavirus

    Identifying Characteristics = viral strains identified by antigenic differences in hemaggluttinin & neuroamindase spikes as well as protein coats - antigenic shift which makes immunity very hard to develop & vaccines of limited use, minor annual variation in virus makeup called antigenic drift
  69. Histoplasmosis
    Causative Agent = Histoplasma capsulatum

    Identifying Characteristics = subclinical respiratory infection acquired by inhaling condidia which have accumulated in bird & bat droppings
  70. Pneumocystis Pneumonia
    Causative Agent = Pneumocystis jirovecii

    Identifying Characteristics = primary indicator of AIDS, affects immunosuppressed patients, P. jirovecii has charachteristis of both a protozoan & fungus
  71. Dental Caries (tooth decay)
    Causative Agent = Streptococcus mutans

    Identifying Characteristics = bacteria adhere to teeth using sticky sugars forming plaques, produce acid that destroys enamel
  72. Staphylococcal Food Poisoning
    Causative Agent = Staphylococcus aureus

    Identifying Characteristics = caused by enterotoxin produced in improperly stored foods that are contaminated with bacteria
  73. Shigellosis (bacillary dysentery)
    Causative Agent = Shigella bacteria

    Identifying Characteristics = ulceration of intestines & blood & mucous in stool, abdominal cramps & fever
  74. Salmonellosis
    Causative Agent = Salmonella enteric

    Identifying Characteristics = nausea, pain, diarrhea occurs after eating large numbers of salmonella, can prevent by proper cooking of food
  75. Typhoid Fever
    Causative Agent = Salmonella typhi

    Identifying Characteristics = transmitted in feces, fever & malaise over 2 week period, bacteria can be harbored in gall bladder of carriers
  76. Cholera
    Causative Agent = Vibrio cholerae

    Identifying Characteristics = exotoxin alters membrane permeability of intestine resulting in vomiting & diarrhea
  77. E. coli Gastroenteritis
    Causative Agent = Escherichia coli

    Identifying Characteristics = "traveler's diarrhea," Shiga toxin producing strains of E. coli cause inflammation & bleeding of colon, can also affect kidneys
  78. Peptic Ulcer Disease
    Causative Agent = Helicobacter pylori

    Identifying Characteristics = bacteria produces ammonia which neutralizes stomach acid allowing bacteria to colonize, lead to peptic ulcer disease
  79. Clostridium difficile - Associated Diarrhea
    Causative Agent = Clostridium difficile

    Identifying Characteristics = occurs following antibiotic therapy leading to diarrhea & colitis, usually acquired in hospitals & nursing homes
  80. Mumps
    Causative Agent = Mumps virus

    Identifying Characteristics = virus enters respiratory tract, causes inflammation of partid glands & pain during swallowing, testes can also become inflamed (orchitis)
  81. Hepatitis A
    Causative Agent = Hepatitis A virus

    Identifying Characteristics = transmitted in food & water, virus grows in intestine, liver, kidney, spleen, & blood, most cases are subclinical
  82. Hepatitis B
    Causative Agent = Hepatitis B virus

    Identifying Characteristics = frequently serious, can be transmitted in blood & other body secretions, infection can be chronic & lead to liver damage & failure
  83. Hepatitis C
    Causative Agent = Hepatitis C virus

    Identifying Characteristics = transmitted in blood, disease is usually mild but can become chronic & cause liver damage, kills more people than AIDS
  84. Viral Gastroenteritis
    Causative Agent = Rotaviurs or Noravirus

    Identifying Characteristics = causes vomiting & diarrhea, very low infective dose for viruses
  85. Ergot Poisoning
    Causative Agent = Claviceps purpruea

    Identifying Characteristics = caused by mycotoxin from contaminated grains, causes gangrene & hallucinations
  86. Aflatoxin Poisoning
    Causative Agent = Aspergillus flavus

    Identifying Characteristics = caused by aflatoxin, found in peanuts, problem for livestock & linked to liver cirrhosis & cancer in humans in India & Africa
  87. Giardiasis
    Causative Agent = Giardia lamblia

    Identifying Characteristics = causes nausea, abdominal cramping that persists for weeks, transmitted in contaminated water
  88. Cryptosporidiosis
    Causative Agent = Cryptosporidium hominis

    Identifying Characteristics = diarrhea in immunosuppressed, transmitted in water
  89. Ameobic Dysentery
    Causative Agent = Entamoeba hystolyica

    Identifying Characteristics = amoeba feeds on RBCs & GI tract tissues, results in abscesses
  90. Tapeworms
    Causative Agent = Taenia solium (pork) & Taenia saginatus (beef)

    Identifying Characteristics = transmitted in undercooked meat containing cysticerci, adult lives in intestine & sheds eggs in feces
  91. Pinworms
    Causative Agent = Enterobius vermicularis

    Identifying Characteristics = anal itching due to female laying eggs, diagnosis made by finding eggs on scotch tape
  92. Hookworms
    Causative Agent = Necator americanus, Ancyclostoma duodenale

    Identifying Characteristics = hookworm attaches to intestine & feeds off blood & tissue, causes pica (craving for peculiar foods with clay)
  93. Ascariasis
    Causative Agent = Ascaris lumbricoides

    Identifying Characteristics = worms migrate throughout body & can exit through nose, navel, mouth, or anus, transmitted by ingestion of eggs
  94. Trichinellosis
    Causative Agent = Trichinella spiralis

    Identifying Characteristics = larva encyst in muscle tissues of humans & animals, contracted by eating undercooked meat containing larva or chewing fingernails after handling raw infected meat, symptoms can include swelling around eyes, fever, & upset GI tract
  95. The phenomenon by which normal microbiota can prevent pathogens from causing infection is called
    Competitive exclusion
  96. Koch's postulates are criteria for establishing the __ of a disease.
    Etiologic agent
  97. A specific group of symptoms or signs that always accompanies a disease is called
  98. Transmission of pathogens using food or water is referred to as
    Vehicle transmission
  99. Siderophores are proteins made by bacteria to obtain what from the host cells
  100. Visible signs of viral infections are called
    Cytopathic effects
  101. Tetracyclines inhibit protein synthesis by binding to which part(s) of the ribosome
    30S subunit & interfere with tRNA attachment
  102. A difference between natural & semi-synthetic penicillins would include
    • A broader range of activity
    • Resistance to penicillinase
  103. Sulfonamides inhibit folic acid synthesis which is important for
    Synthesis of nucleic acids
  104. Antimicrobial agents that act as competitive inhibitors affect which host proteins?
  105. Drugs that affect peptidoglycan synthesis will damage which type of bacteria the most?
    Gram +
  106. A new class of antibiotics inhibit fatty acid synthesis, which leads to damage to
    Plasma membranes
  107. Antiviral drugs can inhibit viral replication by preventing
    • Uncoating
    • Entry into the host cell