LEGIONELLA Flashcards
Primary human pathogen of Legionnaires disease (atypical pneumonia)
acquired via aerosolization of bacteria from contaminated cooling towers or other environmental
Legionella pneumophila
First member of the family Legionellaceae
Legionella pneumophila
1, accounts for 95% of Legionnaires’ disease
• 2-10 days incubation
• Begin with nonproductive cough, fever, headache, myalgia
• Followed by bloody or purulent sputum, rales, dyspnea, shaking chills
• May lead to dissemination - extrapulmonary infection
IL. pneumophila serogroup
A widely publicized outbreak of pneumonia in Philadelphia during the American Legion convention in 1976. Delegates, _____of them developed pneumonia, and____ of them died.
221
34
____species identified and
more than____ serogroups
____ species from humans
60
70
25
Other species:
L. micdadei
L. longbeachae (notable for exposure to gardening materials)
L. dumoffii
Legionella
• 3 patterns of disease:_____,_____,_____
•______ - the predominant manifestation of legionellosis, top 4 cause of CAP
• ______mortality rate
sporadic
epidemic outbreaks
nosocomial clusters
Pneumonia
15%-30%
Pontiac Fever (flulike illness) is caused by
L. pneumophila serogroups 1 & 6.
intracellular survival within macrophages, cell to cell spread, secretes proteolytic enzymes
Legionella
Yellow / Blue-White
L. steelei
Blue-White
L. bozemanii
L. dumoffii
L. gormanii
L. lytica
L. parisiensis
L. tusconensis
Blue-White or Yellow-Green
L. anisa
Red
L. rubrilucens
No Color
L. cardiac
L. feeleii
L. lansingensis
L. londiniensis
L. nagasakiensis
Yellow-Green
Legionella birminghamensis
L. cincinnatiensis
L. hackeliae
L. jordanis
L. longbeachae
L. maceachernii
L. micdadei
L. oakridgensis
L. pneumophila
L. sainthelensi
L. wadworthii
Legionella: Laboratory Diagnosis
Specimens:
- Treat sputum or other contaminated specimens with_______
Dilute specimens from normally sterile sites with _____ or _____, 1:10, to dilute microbial inhibitors such as complement, antibodies, and antimicrobial agents
0.2N potassium chloride-hydrochloric acid
tryptic soy broth or distilled water
Microscopic examination:
•Pleomorphic, weakly staining, GNB, 1-2 um x 0.5 um in size, intracellular and/or extracellular
Extending safranin counterstaining time to at least 10 minutes can enhance staining intensity
- weakly acid fast in tissue,
• stains best with modified Kinyoun procedure
• L. micdadei
• L. micdadei - weakly acid fast in tissue,
• stains best with…
modified Kinyoun procedure
Faint-staining, pleomorphic GNB can be seen outside of and within macrophages and segmented neutrophils in stained smear.
Legionella
Legionella: Laboratory Diagnosis
Culture
Legionella spp. are fastidious, aerobic bacteria.
DO NOT grow on____
Require______ for growth
Tiny colonies may grow on CHOC that contains_____
SBA
L-cysteine
L-cysteine
- best for Legionella
BYE agar with L-cysteine
BCYE agar with L-cysteine
Contains
a-ketoglutarate
polymyxin B
anisomycin
either vancomycin or cefamandole
BCYE agar
•Colonies: grayish white or blue-green, convex, glistening, 2-4 mm in diameter
Legionella
•Young colonies: “ground-glass” appearance, light gray and granular, periphery pink or light blue or bottle green bands with a furrowed appearance.
•Plates are illuminated with UV, 366 mm
Legionella
• Slow growth (3-5 days)
• Characteristic “ground gass” colony morphology
• Lighty staining gram-negative baclus
• Requires L-cysteine for primary isolation
• No growh on unsupplemented sheep blood agar
• Asaccharolytic
• Catalase or oxidase: weakly positive
Legionella
