DOI: 10.37349/emed.2026.1001424 ISSN: 2692-3106

Suspected triple co-infection with SARS-CoV-2, Legionella pneumophila, and Streptococcus pneumoniae after hot-spring travel: a case report

Ryutaro Hirose, Hidenori Takahashi, Takumi Yasuda, Kota Taguchi, Kanako Furukawa, Yugo Satake, Hiroki Nagamatsu, Naoya Toba, Mio Toyama-Kousaka, Shinichiro Ota, Miwa Morikawa, Masaharu Shinkai
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Bacterial co-infection in patients with coronavirus disease 2019 (COVID-19) can complicate diagnosis because of overlapping clinicoradiologic findings among pathogens. We report a case of suspected triple co-infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Legionella pneumophila (L. pneumophila), and Streptococcus pneumoniae (S. pneumoniae) after hot-spring travel in a post-splenectomy patient. A man in his 70s with a history of subtotal esophagectomy and concomitant splenectomy for esophageal cancer was admitted with fever, worsening productive cough, and altered sensorium. He had recently traveled to a hot spring with a group that included his wife, who also developed a fever and was diagnosed with COVID-19. On admission, results of urinary antigen tests for L. pneumophila and S. pneumoniae were positive, a SARS-CoV-2 nucleic acid amplification test was positive, and sputum culture yielded S. pneumoniae. Chest computed tomography revealed multifocal bilateral ground-glass opacities, small bilateral pleural effusions, and relatively well-defined right middle-lobe consolidation with air bronchograms in a peribronchovascular distribution. These microbiological and radiological findings supported a suspected triple co-infection rather than COVID-19 alone. Treatment with remdesivir, ceftriaxone, and levofloxacin was initiated, and the patient’s condition improved, with better oxygenation and decreased inflammatory markers. Remdesivir and ceftriaxone were discontinued after 5 days, whereas levofloxacin was continued for 14 days. Follow-up imaging revealed marked improvement, and the patient was discharged. Public health investigations did not detect Legionella at the hot-spring facility or identify any additional linked cases. This case highlights the importance of prompt pathogen-directed evaluation when COVID-19 pneumonia is accompanied by a relevant exposure history, host risk factors, and atypical imaging findings.

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