Please enable JavaScript.
Coggle requires JavaScript to display documents.
Micro - Legionella Pneumophila (Legionnaire's disease (Tx (beta…
Micro - Legionella Pneumophila
intro
pneumophila = lung-loving
over 70 serotypes of the Legionella spp
L pneumophila causes 85% of human legionella disease
non-capsulated gram -ve bacillus
strict aerobe
has flagellae
sporadic/endemic disease
causes 2-9% of CAP (under-Dxed)
ubiquitous , but naturally in water
esp aerosol generators (AC units, taps, shower heads, car washes, domestic piped water supplies, cooling towers, nebulisers, humidifiers, jacuzzis, fountains)
colonisation enhanced by warm temp (29-42 degrees), stagnation, sediment, scale
Legionnaire's disease
twice as common in men
average onset age = 50-60 (rare under 30)
mortality = 15-20%
higher in those with suppressed cell-mediated immunity (e.g. transplant recipients) + of Tx is delayed
Pontiac fever
brief sudden abrupt onset of ILI
self-limiting fever, headache, chills, dry cough
can progress to multi organ disease
kidneys
proteinuria
haematuria
renal tubular acidosis leading to hyponatraemia
GIT
CNS
liver
2-10 days incubation
difficult to see by gram stain
Dx
culture
of sputum, tracheal aspirate or BAL
requires specific medium (buffered charcoal yeast extract - BCYE agar) with antibiotics to inhibit growth of normal flora
notify lab in advance
colonies appear 2-3 days after incubation
urinary antigen detection
most common
rapid
serology
Ig detectable on day 8 of illness, 4-fold rise 2 wks later (in convalescent stage)
not routinely available
immunofluorescent microscopy
high specificity, lacks sensitivity (false -ve risk)
tracheal aspirate, bronchial lavage + lung Bx
predisposing factors
old age
smoking
immunosuppression
Tx
beta-lactams not effective
drugs with good intracellular penetration needed
resp fluoroquinolones (levofloxacin)
macrolides (azithromycin/clarithromycin)
add rifampicin in v ill
Prevention
avoid areas of water stagnation, let taps + showers run, clean + descale shower heads, clean water tanks, chlorinate water supply, keep hot water > 50 degrees + cold water < 20 - (thermostatic mixing okay)