![]() ![]() ![]() The urine antigen test does help to overcome this problem as it can detect infection within 2-3 days of symptom onset and remains positive for at least 1 month following resolution of the illness. 6 Adding to the difficulty in detection, Legionella is easily treated by empiric therapies, such as macrolides, that cover atypical infections therefore, delays in testing further reduce sensitivity. pneumophila and 14 days for non-pneumophila strains (Image 2). When culture is attempted, nutrient enriched BCYE agar is required and the timeframe for growth must be increased to 5 to 7 days for L. 5 The gold standard for diagnosis is culture of lower respiratory secretions, however it is a fastidious organism that is not easily picked up on gram stain or grown on standard media. Despite commonly being thought of as an exotic pathogen, Legionella is known to cause between 2%-15% of community-acquired pneumonia cases in the United States and Europe. This case reviews a typical presentation of Legionnaire’s disease and highlights several diagnostic pearls worth remembering. Characteristic signs that may cause a treating physician to think of Legionella infection include a constellation of symptoms that include diarrhea, hyponatremia, and elevated liver function tests. 3 Legionella infections most commonly cause community-acquired pneumonia after inhalation of aerosols and can less frequently cause a self-limited febrile syndrome known as Pontiac Fever. longbeachae is the predominant human pathogen. pneumophila, and more specifically its serogroup 1. 2 In North America, upwards of 90% of cases are caused by L. At least 26 of these species are pathogenic in humans, however only a few are responsible for the vast majority of known cases. 1 There are over 60 known species of Legionella with each consisting of a varied number of serogroups. Legionella is a genus of aerobic, gram negative, intracellular pathogens that are most often found in soil and water. Representative example of Legionella pneumophila on Buffered Charcoal Yeast Extract (BCYE) media with small wet gray colonies. Computed tomography images of the chest without contrast demonstrates consolidation and “crazy paving” patterns of radiographic pathology. Ultimately, the diagnosis of Legionnaire’s Disease was made by the positive urine antigen test. Blood and sputum cultures were negative as was the T-spot. A legionella urine antigen test was ordered a short time later following an infectious disease consult.ĬBC and CMP were significant for leukocytosis (19 x 10 9 /L), hyponatremia (130 mmol/L), and transaminitis (AST: 97, ALT: 91). Initial laboratory assessments included CBC, CMP, blood and sputum cultures, and a T-spot. Chest x-ray revealed a lobar pneumonia and a CT chest showed ground-glass opacities with superimposed interlobular thickening and intralobular septal thickening, commonly referred to as “crazy-paving” (Image 1). Upon presentation, he was found to meet sepsis criteria for fever of 105° F, white blood cell count of 19 x 10 9 /L, and tachycardia. A 41 year old male with a past medical history significant for HIV presented to the emergency department with complaints of a fever, shortness of breath, cough, myalgias, diarrhea, and dark urine for five days. ![]()
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