LEGIONELLA Flashcards
- Faintly staining, thin, gram-neg, bacillary or
coccobacillary - Fastidious, Aerobic, motile and noncarbohydrate fermenting
Legionella
o Legionella pneumophila
o Legionella micdadei (Pittsburg
pneumonia Agent)
o Legionella bozemanii (WIGA Agent)
o Legionella dumoffii
Legionella species
● Only genus in the family Legionellaceae
● Primarily acquired through inhalation
Legionella
catalase and gelatinase;
weak-positive in
(+)
oxidase
Major reservoirs of legionella
Hot water system, cooling towers
and evaporative condensers.
They can infect and multiply within some freeliving amoebe/amoeba (species of Hartmanella,
Acanthamoeba and Naegleria), ciliated protozoa
(Tetrahymena), and biofilms
Characteristics of Legionella:
isolated from
legionella
lakes, rivers, hot springs and mud
They can tolerate up to _______
3 mg/L of chlorine, and
thus resist water disinfection treatments.
Cannot grow
legionella
on routine media: BAP
BCYE w/ L-cysteine (pH 6.9)
-Agent of Legionnaire’s disease (1,4 and 6)
and Pontiac fever.
Legionella pneumophila
● Medium
● Invades the bronchoalveolar macrophages,
which is a facultative intracellular pathogen.
● Isolated in air-conditioned units, cooling
towers, humidifiers and nebulizers
Legionella pneumophila
Aka: legionelliosis (febrile and pneumonic
illness)
● Symptoms: High fever, non-productive
cough, headache, neurological and severe
bronchopneumonia
Legionnaire’s disease
Non-fatal respiratory infection
Main symptom is pneumonia.
Pontiac fever
● MOT for Legionnaire’s disease
: Airbone spread, inhalation of aerosol
● Symptoms: for Legionnaire’ s disease
High fever, non-productive
cough, headache, neurological and severe
bronchopneumonia
most
common method for Legionnaire’s disease.
Indirect Fluorescent Antibody (IFA)
detecting
common Legionella species in LRT. (+)
yellow or green-colored bacilli.
Direct Fluorescent Antibody
Rapid methods
● DNA test (PCR)
● Urine antigen test
detects L. pneumophila
as early as 3 days from infection
Urine antigen test:
Culture
Selective Media for Legionella
BCYE with L-cysteine, ferric salt
and -ketoglutarate
weakly acid-fast
L. micdadei
intracellularly and extracellulary
located in phagocytes
Legionella
● Faint staining, undetectable in Gram
staining.
● Prolonging smear for 10 minutes
Staining
Culture used in Legionella and its appearance
Buffered Charcoal Yeast Extract
appear sticky and exhibit a ”rainbow color”
