Clinical characterization and diagnosis of 14 patients with Chlamydia psittaci pneumonia

To investigate the clinical features, diagnostic approaches, and therapeutic strategies for Chlamydia psittaci (C. psittaci) pneumonia.

We conducted a retrospective analysis of 14 patients diagnosed with C. psittaci pneumonia between December 2021 and February 2025 at The People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China. Diagnosis was confirmed via metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF). Clinical manifestations, laboratory findings, imaging characteristics, treatment regimens, and outcomes were systematically analyzed.

The cohort comprised seven males and seven females, aged 46-83 years. A documented history of avian exposure was present in 57.1 % (8/14) of patients. All patients presented with high fever. Lab tests showed increased inflammatory markers (CRP, ESR, d-dimer) in all patients. White blood cell counts were elevated in seven patients and normal in seven others. Neutrophilia occurred in 11 cases and lymphopenia in 13. Elevated procalcitonin (10 cases), LDH (12 cases), creatine kinase (8 cases), and transaminases (ALT: 7 cases; AST: 9 cases) were documented. Electrolyte disturbances included hypokalemia (6 cases), hyponatremia (9 cases), and hypochloremia(13 cases). Eight patients had renal dysfunction (high creatinine/urea), six showed hyperbilirubinemia. Chest imaging revealed varied lung infiltrations: consolidations, ground-glass opacities, nodular shadows, and patchy infiltrates. All cases were confirmed by mNGS and effectively treated with tetracyclines or fluoroquinolones.

C. psittaci pneumonia frequently presents with sepsis-like symptoms and rapid clinical deterioration. Early diagnosis using mNGS is crucial for guiding timely antimicrobial therapy, significantly improving patient outcomes, especially in cases where conventional diagnostics may be limited or delayed.