Legionellosis can be diagnosed by testing for
antigen in the urine of infected patients, and most cases are diagnosed in this fashion. Note that urine antigen testing only identifies
serogroup 1, not other serogroups.
of all species and serogroups can also be identified by culturing from bronchoalveolar lavage samples. Sputum culture can also be utilized, but is less sensitive than culture of the lower respiratory tract. Special media is necessary to isolate
Testing for legionellosis should be considered particularly in patients who have failed outpatient antibiotic therapy for community-acquired pneumonia and patients with severe pneumonia, such as those requiring intensive care.