Legionella Flashcards
Most important Legionella species
Legionella pneumophilia
Morphology of L. pneumophilia
lab media: bacilli
tissues: coccobacilli
Gram negative (poor gram stain)
Growth of L. pneumophilia
facultative intracellular parasites
how is L. pneumophilia spread? where is is present?
aerosols (not person to person contact)
present in natural water
risk factors for L. pneumophilia?
** immunocompromised and elderly (not a disease of healthy, young people)
smoking, chronic lung disease, malignancy, TLR5 polymorphisms (has flagella)
Disease of L. pneumophilia?
Legionnaire’s disease
Pontiac fever
Description of Legionnaire’s disease
severe pneumonia
high mortality rate
low attack rate- only immunocompromised and elder get sick
antibiotics required
Description of Pontiac disease?
flu-like symptoms (no pneumonia)
low mortality rate
high attack rate- get it, get sick
self-limiting- no antibiotics required
Pathogenesis/virulent factors of L. pneumophilia
attachment and invasion of alveolar macrophages (complement binding, type IV pili, coiling phagocytosis)
inhibit phagosome acidification, phagolysosome fusion
formation of replicative vacuole which is associated with ribsomes and Er
Dot/Icm secretion system- important for formation of replicative vacuole
intracellular replication and cell lysis
Diagnosis of L. pneumophilia
poor gram stain Gimenez stain for smears Dieterle stain for tissues urine antigen test direct fluorescent Ab test from sputum sample
L. pneumophilia treatment
Azithromycin
fluoroquinolone (levofloxacin)
** Legionella produce B-lactamases so cant use B-lactam antibiotics**
Legionella prevention
water treatment
