Severe pneumonia caused by Legionella pneumophila associated with Tropheryma whipplei: A case report

RATIONALE: Legionella pneumophila (LP) and Tropheryma whipplei (TW) have been identified as pathogens that can coexist in sewage environments, which can both cause pneumophila and can impact various organs, leading to extrapulmonary manifestations. It is rare to find literature on pneumonia caused by atypical pathogens, such as the combination of LP and TW. There are no reports on specific drug treatments for such combined infections. PATIENT CONCERNS: A 55-year-old male with no underlying diseases developed community-acquired pneumonia. His condition worsened after empirical treatment with piperacillin/tazobactam. He subsequently experienced adverse drug reactions after using moxifloxacin. DIAGNOSES: Pulmonary infection, pulmonary bullae. INTERVENTIONS: After admission, the patient was treated with piperacillin/tazobactam and moxifloxacin for anti-infection. He also underwent a bronchoscopy of the lungs, and the alveolar lavage fluid was tested using targeted next-generation sequencing. The results identified pathogens such as LP and TW. The anti-infection regimen was then adjusted to a combination of ceftriaxone and levofloxacin. Symptomatic treatments were also provided, including expectorant therapy, liver protection, and nutritional support. OUTCOMES: The patient was discharged after showing signs of improvement and was subsequently monitored at an outpatient clinic. LESSONS: When empirical antibiotic therapy for pneumonia is ineffective, infections caused by atypical pathogens should be considered. To prevent progression to severe pneumonia and even patient death, the precise use of antibiotics is beneficial for improving patient outcomes. However, the diagnosis of atypical pathogens is challenging, and the selection of drugs also needs to be considered from multiple aspects.