Yesterday, the 7th mortality from legionella in NYC occurred. There have been 71 cases since July 10, all of them in the South Bronx after Legionella was found in cooling towers. This bacteria typically live in reservoirs of water or humidified spaces. It is a common cause (2 to 9 percent) of community-acquired and hospital-acquired pneumonia known as Legionnaire’s disease. The NYC Department of Health has issued suggestions on diagnosis and management of these patients; new cases should be reported to 866-NYC-DOH1 (1-866-692-3641).
Clinical symptoms include typical symptoms of pneumonia (cough, fever, SOB), but have a high suspicion for this organism if your patient also endorses GI symptoms (nausea/vomiting, diarrhea, abdominal pain) and/or neurologic symptoms (confusion, headache).
The initial diagnostic test that should be ordered in the ED is a urinary antigen test although sensitivity is highly variable. At Mount Sinai Hospital, this test is performed in house and will result in 1 hour. Sputum cultures should also be sent and this is the most important test for definitive diagnosis; be sure to indicate that the culture is for legionella as special medium is used. Laboratory abnormalities include hyponatremia, thrombocytopenia, and LFT changes. There is no specific finding on chest XR that would narrow your diagnosis to legionella.
The most susceptible patients are those who are elderly, diabetic, smokers, and immunosuppressed–antibiotics should be initiated immediately. Although there are no RCTs comparing the two, flouroquinolones (levofloxacin) and macrolides (azithromycin) are equally effective. For recently hospitalized patients and those from nursing homes, levofloxacin is the antibiotic of choice.