Pulmonary infection due to emerging Lophomonas pathogen in immunocompetent patients: Two case reports.

Lophomoniasis is a new emerging parasitic disease caused by Lophomonas spp., a protozoan that predominantly resides in a commensal relationship within the hindgut of cockroaches. This pathogen is known to affect the lower respiratory tract in humans, resulting in clinical manifestations such as cough, sputum production, and shortness of breath. We present two case studies involving a 54-year-old- and a 38-year-old male, both with a history of cigarette smoking but no known underlying medical conditions. These individuals presented at the emergency room with respiratory symptoms and were subsequently evaluated. No significant abnormalities were shown on the lung computed tomography scan in Case 1, whereas empyema was observed in the right lung in Case 2. Analysis of bronchoalveolar lavage fluid from each patient revealed Lophomonas spp., an emerging protozoan pathogen, by microscopic examination. Based on these findings, metronidazole was administered to both patients, resulting in successful treatment of the infection. These cases highlight that Lophomonas spp. is a significant respiratory pathogen capable of causing a spectrum of disease in immunocompetent individuals, from mild bronchitis to severe pneumonia with complications. They emphasize the critical importance of including lophomoniasis in the differential diagnosis for persistent or atypical respiratory infections. Timely treatment with metronidazole was effective, resulting in clinical resolution.