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Legionnaires' Disease or legionellosis is caused by what bacteria? What does it present as?
- Legionella pneumophilia
- Presents as acute pneumonia/ acute respiratory infection
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What kind of agar do your culture Legionella on?
Charcoal yeast extract agar
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What bacteria do you culture on Charcoal Yeast Extract Agar? Is this a fastidious organism?
Legionella
- No, charcoal is present because it removes impurities.
- "Legionnaires must be pure."
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Microscopically where is Legionella bacteria found?
Facultative intracellular parasite
Found as an intracellular parasite in free-living protozoa (amoeba's etc.)
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Which species and serogroup of Legionella causes most cases in the US?
L. pneumophila, sergroup 1 (Lp-1)
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Legionella:
1) Gram-P/N
2) Aerobic/Anaerobic
3) Capsule?
- 1) Gram-N
- 2) Aerobic
- 3) Non-encapsulated
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Legionellosis: Endogenous or exogenous infection?
Exogenous (environmentally-friendly...because obviously you can't just say exogenous)
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2 Forms of Legionellosis
- 1) Legionnaires' Disease: Pneumonia potentially fatal
- 2) Pontiac Fever: Self-limiting influenza-like
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Potentially fatal pneumonia form of Legionella
Legionnaire's Disease
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Self-limiting influenza-like form of Legionella
Pontiac Fever
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Which form of Legionellosis occurs as an epidemic?
Pontiac Fever ("That's why I hate pontiacs")
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Which form of Legionellosis can occur as an epidemic, sporadically, or as a nosocomial infection?
Legionairre's Disease
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Can Legionellosis be transmitted person-to-person?
- No
- Thought to be aerosolized infection
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When is one most likely to get Legionnaire's Disease? Does it require tx?
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When is one most likely to get Pontiac Fever? Does it require tx?
Year round, self-limited
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Whichis more fatal, Legionnaires' Disease or Pontiac Fever?
Legionnaire's Disease is more likely fatal (15-20% or higher) than Pontiac fever (<1%)
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Legionella: Produces inhibitor of ________
oxidative burst
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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.)
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Name 3 enzymes Legionella releases into growth medium.
Hemolysin, protease, aminopeptidase
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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
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Name 3 Predisoposing factors for Legionella and 2 environmental factors.
- Cigarette smoking
- Chronic lung disease
- Immunosuppression
- High humidity
- Increased rainfall
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Does Legionella have to be sent to a lab for diagnosis?
Yes (Legionella = Lab)
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In the Legionella, Urinary Antigen Test what is detected?
LP-1 (pneumophilia specific)
Culture test allows you to grow all species and serogroups.
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Name 3 problems clinically with Legionella pneumophilia.
- Misdiagnosis
- 25% mortality rate
- Can't perform susceptibility testing.
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How do you treat Legionellosis?
Fluoroquinolones, Macrolides (Legionnaires are For her Majesty!)
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Which bacteria is more commonly seen in an ICU type setting?
Acinetobacter baumannii
Increased occurrence with increased stay.
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Gram-N rods of Moraxellaceae family
Acinetobacter baumannii
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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
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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.
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What can be grown on MacConkey media but doesn't ferment?
A. baumannii
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Which organism doesn't ferment lactose and is oxidase negative?
Acinetobacter baumannii
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Ubiquitous organism that is found in pasteurized milk and frozen foods (as well as soil, sink traps, etc.)
Acinetobacter baumanni
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Which organism is important in soil demineralization? Where does it colonize healthy adults?
- Acinetobacter baumannii
- Colonizes skin of 25% of healthy adults
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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.
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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
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What cause of meningitis can look VERY similar to N. meningitidis on a gram stain?
Acinetobacter baumannii
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Most common cause of wound infections in Iraqi war veterans.
Acinetobacter baumannii
(A cine sobra Baumanni, Iraq)
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Spread of ____ is a concern with A. baumannii
- MDRAB (Multi-Drug Resistant)
- Can rapidly acqure antibiotic resistance in addition to its intrinsic antibiotic resistance.
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MDRAB
1) ___ kb resistance island
2) ___ resistance genes in this island
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How was the MDRAB resistance island acquired?
Horizontally, not acquired as a single element
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Name 3 bacteria that contributed to the resistance island of MRAB. Which bacteria contributed the most?
- Pseudomonas (44%)- contributed the most
- Salmonella
- E. coli
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What are the known virulence factors of A. baumannii?
- Polysaccharide capsule
- LPs
- NO KNOWN CYTOTOXINS
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_______ are important in protecting lungs from A. baumannii
Neutrophils (problem for neutropenic patients)
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