5- Legionnaires Flashcards
what is the most common manifestation of legionnaires disease
pneumonia
what two conditions can legionella cause
- Legionnaires diseases
- Pontiac fever (self limiting acute febrile illness)
rare extrapulmonary manifestations of legionella
cellulitis, abscesses, endocarditis, meningitis
T/F pneumonia caused by legionella is clinically and radiographically similar to other forms of pnuemonia
T
common symptoms of legionnaires
fever, cough, dyspnea, (fever and fatigue before cough), rales and signs of consolidation on physical exam (patchy unilobular infiltrates which progress to consolidations)
How is legionella obtained
through exposure to contaminated water or soil
signs that make you thing of legionnaires pneumonia and not CAP
- nausea, vomiting, diarrhea
- hyponatremia
- elevated hepatic transaminases
- CRP >100 Mg/L
- failure to respond to treatment of pneumonia with B lactams
mortality of legionnaires disease is
1-10%
local complications of legionnares are
empyema and lung abscess
T/F clinical features of legionnaires disease do not appear to vary with the infecting species or serotypes
T
Differences between the two species of legionnaires bacteria
L. pneumophilia: is found worldwide, and is acquired from contaminated water sources in late summer and early fall
L. longbeachae: has more restricted geographical location (australia, new zealand), is acquired from soil in late spring and early summer
T/F legionella infection occur sporadically in pts with CAP
T
T/F lab testing is necessary for diagnosis of legionnaires
T
who to test for legionella
an inclusive approach is taken
- all pts with mod/sev CAP or those that need hospitalisation
- any pt with CAP or nosocomila penumonia who has known exposure to legionella
- immunocompromised pts
tests for dx of legionella infection
nucleic acid detection (PCR)
urine antigen tests***
culture
T/F sensitivity of urine antigen tests ranges from 70-80%, and specificity approaches 100% in pts with legionnaires due to L. pneumophilia serotype 1
T
T/F legionella antigens can be found in urine one day after symptom onset and persist for days to weeks
T (the turnaround time for the assay is a few hours)
major disadvantage of urine antigen assay in legionella
it only detects L. pneumophilia serotype 1 (this causes 80% of cases in most of the world apart from australia)
symptoms of pontiac fever
non specific, fever, headache, chills, myalgias, nausea, vomiting, diarrhea. Symptom onset is 4-60 hours after exposure
duration of illness in pontiac fever
1-9 days, it resolves without specific therapy
does pontiac fever have signs of lower respiratory tract infection
no
when would you suspect pontiac fever
based on epidemiological exposure; bc it is self limiting, testing is not usually performed
extrapulmonary legionella infection occurs in
immunocompromised cases
T/F cases of extrapulmonary legionella is caused by legionella species other than L. pneumophilia
T
dx of extrapulmonary disease in legionella
detection of legionella at the affected site, via culture or PCR
tx of legionnares dx
levofloxacin, azithromycin for min of 5 days (both bactericidal), they achieve high intracellular concentrations and penetrate lung tissue, and are active agaisnt all legionella species that cause human infection
T/F up to 44% of legionnaires dx pts need ICU admission
T
do pts with confirmed or suspected legionella infections need isolation
no
primary method for controlling legionella infection in water supply
copper silver ionization, hyperchlorination, thermal shock, chlorine dioxide, monochloramine, point of use filters
