Micro Test 3: Legionella

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  1. Legionnaires' Disease or legionellosis is caused by what bacteria?  What does it present as?
    • Legionella pneumophilia
    • Presents as acute pneumonia/ acute respiratory infection
  2. What kind of agar do your culture Legionella on?
    Charcoal yeast extract agar
  3. What bacteria do you culture on Charcoal Yeast Extract Agar?  Is this a fastidious organism?

    • No, charcoal is present because it removes impurities. 
    • "Legionnaires must be pure."
  4. Microscopically where is Legionella bacteria found?
    Facultative intracellular parasite

    Found as an intracellular parasite in free-living protozoa (amoeba's etc.)
  5. Which species and serogroup of Legionella causes most cases in the US?
    L. pneumophila, sergroup 1 (Lp-1)
  6. Legionella:
    1)  Gram-P/N
    2)  Aerobic/Anaerobic
    3)  Capsule?
    • 1)  Gram-N
    • 2)  Aerobic
    • 3)  Non-encapsulated
  7. Legionellosis:  Endogenous or exogenous infection?
    Exogenous (environmentally-friendly...because obviously you can't just say exogenous)
  8. 2 Forms of Legionellosis
    • 1)  Legionnaires' Disease:  Pneumonia potentially fatal
    • 2)  Pontiac Fever:  Self-limiting influenza-like
  9. Potentially fatal pneumonia form of Legionella
    Legionnaire's Disease
  10. Self-limiting influenza-like form of Legionella
    Pontiac Fever
  11. Which form of Legionellosis occurs as an epidemic?
    Pontiac Fever ("That's why I hate pontiacs")
  12. Which form of Legionellosis can occur as an epidemic, sporadically, or as a nosocomial infection?
    Legionairre's Disease
  13. Can Legionellosis be transmitted person-to-person?
    • No
    • Thought to be aerosolized infection
  14. When is one most likely to get Legionnaire's Disease?  Does it require tx?
    • Summer-fall
    • Requires tx
  15. When is one most likely to get Pontiac Fever?  Does it require tx?
    Year round, self-limited
  16. Whichis more fatal, Legionnaires' Disease or Pontiac Fever?
    Legionnaire's Disease is more likely fatal (15-20% or higher) than Pontiac fever (<1%)
  17. Legionella: Produces inhibitor of ________
    oxidative burst
  18. Which bacteria produces an enzyme that inhibits oxidative burst?  What does this allow the bacteria to do?
    • Legionella
    • Allows bacteria to survive encounters with phagocytic cells (ie. macrophages, neutrophils, etc.)
  19. Name 3 enzymes Legionella releases into growth medium.
    Hemolysin, protease, aminopeptidase
  20. Legionella is found in ____ and is usually transmitted by _____.  Can form biofilms on?
    • aerosols (showers and respiratory therapy equipment, basically any water source that aerosolizers the water)
    • surface & drinking water
    • biofilms= silicone and rubber
  21. Name 3 Predisoposing factors for Legionella and 2 environmental factors.
    • Cigarette smoking
    • Chronic lung disease
    • Immunosuppression

    • High humidity
    • Increased rainfall
  22. Does Legionella have to be sent to a lab for diagnosis?
    Yes (Legionella = Lab)
  23. In the Legionella, Urinary Antigen Test  what is detected?
    LP-1 (pneumophilia specific)

    Culture test allows you to grow all species and serogroups.
  24. Name 3 problems clinically with Legionella pneumophilia.
    • Misdiagnosis
    • 25% mortality rate
    • Can't perform susceptibility testing.
  25. How do you treat Legionellosis?
    Fluoroquinolones, Macrolides (Legionnaires are For her Majesty!)
  26. Which bacteria is more commonly seen in an ICU type setting?
    Acinetobacter baumannii

    Increased occurrence with increased stay.
  27. Gram-N rods of Moraxellaceae family
    Acinetobacter baumannii
  28. Acinetobacter baumanni:
    1)  Gram-P/N
    2)  Family?
    3)  Motile?
    4) Ferments?
    5)  Capsule?
    6)  Oxidase-P/N
    • 1)  Gram-N
    • 2) Moraxellaceae family
    • 3)  Non-motile
    • 4)  Non-fermeter
    • 5)  Encapsulated
    • 6)  Oxidase-N
  29. How many species of the Moraxellaceae family are there currently?  What is the most frequent clinical isolate?
    17, A. baumannii is the most frequent clinical isolate.
  30. What can be grown on MacConkey media but doesn't ferment?
    A. baumannii
  31. Which organism doesn't ferment lactose and is oxidase negative?
    Acinetobacter baumannii
  32. Ubiquitous organism that is found in pasteurized milk and frozen foods (as well as soil, sink traps, etc.)
    Acinetobacter baumanni
  33. Which organism is important in soil demineralization?  Where does it colonize healthy adults?
    • Acinetobacter baumannii
    • Colonizes skin of 25% of healthy adults
  34. Which organism causes suppurative infection in virtually every organ system?  Usually limited infection unless host is immunocompromised.
    Actinobacter bacumanni

    I don't know why they even say immunocompromised.  Every organism is going to be more likely to infect you if you don't have an immune system.
  35. Clinical manifestations of A. baumannii (5)
    • Pneumonia:  Often ICU ventilated patient (mortality >70%)
    • Bacteremia:  Associated with respiratory infections and IV catheters.  Can very rarely cause endocarditis.
    • Genitourinary
    • Intracranial Infection: meningitis (can be morphologically confused with N. meningitidis on gram stain.)
    • Soft Tissue Infection:  Cellulitis
  36. What cause of meningitis can look VERY similar to N. meningitidis on a gram stain?
    Acinetobacter baumannii
  37. Most common cause of wound infections in Iraqi war veterans.
    Acinetobacter baumannii

    (A cine sobra Baumanni, Iraq)
  38. Spread of ____ is a concern with A. baumannii
    • MDRAB (Multi-Drug Resistant)
    • Can rapidly acqure antibiotic resistance in addition to its intrinsic antibiotic resistance.
  39. MDRAB
    1) ___ kb resistance island
    2) ___ resistance genes in this island
    • 86
    • 52
  40. How was the MDRAB resistance island acquired?
    Horizontally, not acquired as a single element
  41. Name 3 bacteria that contributed to the resistance island of MRAB.  Which bacteria contributed the most?
    • Pseudomonas (44%)- contributed the most
    • Salmonella
    • E. coli
  42. What are the known virulence factors of A. baumannii? 
    • Polysaccharide capsule
    • LPs
  43. _______ are important in protecting lungs from A. baumannii
    Neutrophils (problem for neutropenic patients)
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Micro Test 3: Legionella
2012-11-21 20:41:52

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