Microbiology Exam 2

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HuskerDevil
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Microbiology Exam 2
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2010-10-04 10:00:13
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DPAP2012 Microbiology Clostridia Bacillus Gram Positive Aerobic Anaerobic Gram Negative Cocci Gram Neg Rods Unusual Bacteria
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DPAP2012 Microbiology Clostridia Bacillus Gram Positive, Aerobic and Anaerobic Gram Negative Cocci, Gram Neg Rods, Unusual Bacteria
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  1. Medically Important Gram Positive Rods (Aerobic)
    • Bacillus
    • Corynebacterium
    • Erysipelothrix
    • Listeria
    • Gardnerella
  2. Bacillus Virulence Factors
    • Endospores
    • Enterotoxins
  3. Etiological Agent of Anthrax
    Bacillus anthracis
  4. Clinical Presentations of Anthrax
    • Cutaneous
    • Gastroenteritis
    • Inhalation (100% fatality)
  5. Clinical Presentations of B. cereus
    • Gastroenteritis (mediated by enterotoxins)
    • Ocular (rapid, progressive destruction following trauma)
  6. Severity of B. Cereus Gastroenteritis
    • Mild, self-limiting disease.
    • N/V or diarrhea.
    • Often ignored as food bug
  7. Etiological Agent of Diphtheria
    Corynebacterium diphtheriae
  8. Diphtheroids
    Non-pathogen species that often find their way into lab media
  9. Microscopic Morphology of Erysipelothrix
    Small, thin rods that form long filaments
  10. Microscopic Morphology of Listeria
    Small, paired coccobacilli
  11. Erysipelothrix associated with human disease
    E. rhusiopathiae
  12. Erysipelothrix disease
    Endocarditis
  13. #1 Cause of mortality in foodborne illnesses
    Listeria monocytogenes
  14. Methods of transmission for Listeria monocytogenes
    Contaminated food (unpasteurized milk), vertical, zoonotic.
  15. Medically Important Gram Positive Rods
    • Actinomyces
    • Clostridium
    • Lactobacillus
    • Mobiluncus
    • Propionibacterium
  16. Gram positive Rod genus with filamentous morphology
    Actinomyces (resembles hyphae)
  17. Actinomyces species most commonly involved in human infections
    A. israelii
  18. Spore forming genera
    Bacillus and Clostridium
  19. Virulence of serotypes of Clostridium perfringens
    5 serotypes, type A most responsible for human disease
  20. Virulence factors of Clostridium perfringens
    Arsenal of toxins known as lethal toxins. A-toxin (lecithinase)
  21. Virulence factors of C. tetani
    • hemolysin
    • neurotoxin (tetanospasmin) responsible for clinical expression of tetanus by blocking neurotransmitter release
  22. Clinical presentations of botulism
    • Food borne (foods with low acid content)
    • Infant botulism (used to be caused by giving kids honey)
    • Wound botulism
  23. Virulence factors of C. diff
    Enterotoxin and Cytotoxin
  24. Clinical presentations of Lactobacillus
    Transient bacteremia, endocarditis, opportunistic septicemia
  25. Gram staining of Mobiluncus and Gardnerella
    On gram stain appear Gram - or gram variable, but have a gram positive cell wall, show antibiotic susceptibility similar to Gram + bacteria, lack endotoxin.
  26. Colonization of Mobiluncus and Gardnerella
    Colonize female genital tract in large numbers
  27. Most medically important species of Propionibacterium
    P. acnes
  28. medically important species of Clostridium
    • C. perfringens
    • C. botulinum
    • C. tetani
    • C. dificile
  29. C. perfringens
    • What disease(s) does the microbe cause?
    • Mild gastroenteritis to severe myonecrosis (gas gangrene)

    • Where (ie site in the body) is the disease?
    • Wound that becomes infected w/ spores from environment

    • Why is the microbe able to cause disease?
    • Virulence factors: arsenal of toxins known as “lethal toxins”
    • Ά-toxin ( a lecithinase) is produced in large quantities by type A strains of C. perfringens
    • Lecithinase: lyses all types of cells
    • Form spores

    • Who is at risk for the disease?
    • People w/ open wounds

    • How is the disease transmitted?
    • Grows easily and rapidly in vitro
    • 5 serotypes: A-E
    • Type A responsible for most human disease
  30. C. tetani
    • terminal endospore is characteristic (looks like drumstick)
    • difficult to grow in vitro

    • What disease(s) does the microbe cause?
    • Tetanus
    • Muscle spasms/ paralysis

    • Where (ie site in the body) is the disease?
    • GI tract?

    • Why is the microbe able to cause disease?
    • Spore-former
    • hemolysin
    • neurotoxin (tetanospasmin): responsible for clinical expression of tetanus by blocking neurotransmitter release

    • Who is at risk for the disease?
    • tetanus now rarely seen in developed countries but still a major problem in developing countries

    How is the disease transmitted?
  31. C. botulinum
    • What disease(s) does the microbe cause?
    • Botulism
    • bacterium divided into 4 groups: I, II, III, IV
    • likely represents 4 different species

    • 3 clinical presentations of botulism:
    • food borne: improper canning; food w/ low acid content
    • infant botulism: caused by giving kids honey– normal flora not fully developed yet
    • Kids can get incidentally by inhalation from soil
    • wound botulism: contaminated wounds

    • Where (ie site in the body) is the disease?
    • GI tract?

    • Why is the microbe able to cause disease?
    • commonly found in soil but disease is rare
    • disease mediated by neurotoxin:
    • these toxins identified as types A-G; are antigenically distinct

    Who is at risk for the disease?

    • How is the disease transmitted?
    • Food
    • Soil/ inhalation
    • Contaminated wounds
  32. C. difficile
    • What disease(s) does the microbe cause?
    • etiologic agent of antibiotic associated colitis (AAC)
    • C diff= most common cause of AAC; other spp of Clostridium can cause AAC too
    • Clinical presentation: have “double-digit” stools (>10 episodes); feel poorly overall

    • Where (ie site in the body) is the disease?
    • GI tract

    • Why is the microbe able to cause disease?
    • normal GI flora in some; disrupted by antibiotics
    • virulence factors: two major toxins
    • toxin A: enterotoxin
    • toxin B: cytotoxin
    • spore formation allows organism to survive in hospital environment

    • Who is at risk for the disease?
    • like MRSA, increasing presence in community outpatient populations

    • How is the disease transmitted?
    • Nosocomial, opportunistic
  33. Describe the virulence factors associated with species of Clostridium.
    Gram positive rods that colonize skin and mucosal surfaces

    • C. diff
    • virulence factors: two major toxins
    • toxin A: enterotoxin
    • toxin B: cytotoxin
    • spore formation allows organism to survive in hospital environment

    • C. botulim
    • commonly found in soil but disease is rare
    • disease mediated by neurotoxin:
    • these toxins identified as types A-G; are antigenically distinct

    • C. tetani
    • Spore-former
    • hemolysin
    • neurotoxin (tetanospasmin): responsible for clinical expression of tetanus by blocking neurotransmitter release

    • C. perfringens
    • Virulence factors: arsenal of toxins known as “lethal toxins”
    • Ά-toxin ( a lecithinase) is produced in large quantities by type A strains of C. perfringens
    • Lecithinase: lyses all types of cells Form spores
  34. Identify the medically important species of Bacillus.
    • B. anthracis:
    • etiologic agent of anthrax
    • anthrax has 3 clinical presentations:
    • cutaneous
    • Gastroenteritis: relatively rare
    • Inhalation: mortality rate 100%
    • Classic sign= wide mediastinum

    • B. cereus:
    • two clinical presentations:
    • gastroenteritis:
    • More common
    • mediated by enterotoxins
    • ocular:
    • Keratoconjunctivitis
    • trauma→ rapid, progressive destruction
  35. Discuss the epidemiology of B. anthracis and B. cereus.
    genus of large Gram positive rods

    • B. anthracis
    • What disease(s) does the microbe cause?
    • etiologic agent of anthrax
    • anthrax has 3 clinical presentations:
    • cutaneous: ulcers w/ lymphadenopathy
    • Gastroenteritis: relatively rare
    • Inhalation: mortality rate 100%
    • Pneumonia and septicemia
    • Classic sign: wide mediastinum

    • Where (ie site in the body) is the disease?
    • Skin, GI, respiratory

    • Why is the microbe able to cause disease?
    • endospores
    • enterotoxins

    Who is at risk for the disease?

    • How is the disease transmitted?
    • Airborne, touch
    • Contaminated animal products

    • B. cereus
    • What disease(s) does the microbe cause?
    • two clinical presentations:
    • gastroenteritis:
    • More common
    • mediated by enterotoxins
    • ocular:
    • Keratoconjunctivitis
    • trauma→ rapid, progressive destruction

    • Where (ie site in the body) is the disease?
    • GI tract, eyes

    • Why is the microbe able to cause disease?
    • endospores
    • enterotoxins: heat stable toxin

    Who is at risk for the disease?

    • How is the disease transmitted?
    • Contaminated food products
  36. Describe the virulence factors associated with these species of Bacillus.
    • Endospores
    • Endotoxins
  37. Describe the epidemiology of Listeria monocytogenes.
    • Gram positive rods
    • VERY COMMON
    • Should always be on differential, esp. w/ immunocompromised pt.s
    • like Erysipelothrix is widely found in animals
    • worldwide distribution: soil, water, vegetation, variety of mammals, fish, fowl
    • #1 CAUSE OF MORTALITY IN FOOD INDUSTRY

    • What disease(s) does the microbe cause?
    • asymptomatic carrier state (1-5%)
    • mono-like sx
    • meningitis, bacteremia, encephalitis
    • in pregnant women: intrauterine death, premature labor, neonatal infection

    Where (ie site in the body) is the disease?

    • Why is the microbe able to cause disease?
    • virulence factors:
    • hemolysin
    • listeriolysin O: avoid phagocytosis
    • ability to survive in cold temperatures (1-40 degrees C)

    • Who is at risk for the disease?
    • uncommon and restricted to distinct immunocompromised populations: neonates, elderly, pregnant women, cancer/transplant patients
    • Early presentation: babies get this but survive. Have abscesses
    • Late presentation: babies get meningitis and poor prognosis

    • How is the disease transmitted?
    • human disease transmitted by contaminated (by animal feces) food (esp. unpasturized milk- soft cheese, cold cuts); vertical, zoonotic
  38. Describe the virulence factors associated with L. monocytogenes.
    • hemolysin
    • listeriolysin O: avoid phagocytosis
    • ability to survive in cold temperatures (1-40 degrees C)
  39. Discuss the epidemiology of Corynebacteria.
    • genus of Gram positive rods: often irregularly shaped (maybe club-shaped)
    • grow readily on most laboratory media

    • What disease(s) does the microbe cause?
    • etiologic agent of diphtheria acute inflammation and necrosis toxemia-> myocarditis, neuropathy, paralysis

    • Where (ie site in the body) is the disease?
    • Very common skin contaminant
    • Nasopharynx larynx

    • Why is the microbe able to cause disease?
    • Toxin production: toxin lethally interrupts prot synthesis in cells and has direct action on myocardium-> myocarditis, and on PNS-> neuropathy and paralysis

    Who is at risk for the disease?

    • How is the disease transmitted?
    • Respiratory or direct contact w/ skin lesion
  40. Describe the virulence factors associated with Corynebacterium diphtheriae.
    Toxin production: toxin lethally interrupts prot synthesis in cells and has direct action on myocardium-> myocarditis, and on PNS-> neuropathy and paralysis

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