60% of non-pneumophila Legionella infections are caused by L. micdadei.CASE PRESENTATIONS: A 45-year-old obese male presented with cough, dyspnea and high fever. Examination showed bilateral rhonchi. Arterial blood gas revealed hypoxemia and respiratory acidosis requiring mechanical ventilation. Presumptive diagnoses of bronchitis and obesity-hypoventilation syndrome were made. Azithromycin and ceftriaxone were started. He developed profound, watery, nonbloody diarrhea of up to 8 liters/day. Metronidazole was added to his regimen. Blood, sputum, urine and stool cultures were unrevealing. Clostridium difficile A toxin assay was repeatedly negative. A CT abdomen was unremarkable. A CT chest demonstrated a 3.2 cm mass in the left lower lobe, hilar lymphadenopathy and pleural effusions (Fig. 1).Sputum direct fluorescent antibody assay was positive for Legionella micdadei. Rifampin was added and subsequently multiple sputum cultures grew L. micdadei.. No stool leukocytes, ova or parasites were identified and the osmotic gap showed secretory diarrhea. Colonoscopy was unremarkable. The patient became afebrile after several days and his diarrhea stopped. Follow-up CT four weeks later showed resolution of the lung mass and lymphadenopathy (Fig. 2).
Expanding, occasionally cavitating, pulmonary nodules have been a dramatic finding in some patients infected by L. micdadei1. Our patient’s pulmonary mass resolved completely after appropriate treatment for L. micdadei.While diarrhea is common in Legionella infections, profuse diarrhea seems to be extremely rare. We could only find one documented case of L. micdadei pneumonia causing massive diarrhea2. The etiology appears to be secretory.CONCLUSIONS: Legionellosis may manifest in many ways presenting a diagnostic challenge. Timely diagnosis and treatment require a high degree of clinical suspicion. The recognition of uncommon presentations with profound diarrhea and/or new onset solitary pulmonary nodule may aid in an earlier suspicion and diagnosis of Legionella infection.
B.I. Medarov, None.