Exploring the clinical characteristics and etiological diagnosis of Chlamydia psittaci pneumonia confirmed by targeted next-generation sequencing: A retrospective observational study

Chlamydia psittaci (C psittaci) is an important causative agent of community-acquired pneumonia (CAP). However, conventional pathogen detection methods are often ineffective in the early diagnosis of CAP, making C psittaci pneumonia challenging to detect. C psittaci ranges from mild, self-limited to acute respiratory failure, and the early identification of this disease can be challenging. Targeted next-generation sequencing (tNGS) of bronchoalveolar lavage fluid has the potential to improve the pathogen identification in C psittaci pneumonia. This retrospective study aims to systematically evaluate the clinical characteristics and etiological diagnostic value of tNGS in patients with C psittaci pneumonia, providing further insights into the diagnosis and management of this disease. We performed a retrospective analysis of samples obtained from 40 patients diagnosed with C psittaci pneumonia using tNGS at Zhengzhou People's Hospital between January 2024 and March 2025. The clinical characteristics, laboratory findings, radiological features, and treatment strategies for each patient were systematically evaluated. The analysis revealed that C psittaci pneumonia was frequently associated with avian or poultry exposure. Predominant clinical manifestations included fever, cough, sputum production, headache, and fatigue. Laboratory tests commonly indicated elevated neutrophil percentage, C-reactive protein, procalcitonin, and interleukin-6 levels, alongside reduced median lymphocyte percentage, eosinophil percentage, and albumin levels. Chest computed tomography scans revealed the presence of unilateral or bilateral pulmonary infiltrates. Upon tNGS-based pathogen identification, antimicrobial therapy was promptly adjusted to doxycycline and moxifloxacin, which resulted in favorable clinical outcomes. Although C psittaci-induced CAP lacks pathognomonic symptoms, characteristic laboratory markers may aid its early identification. The tNGS was found to be a rapid and accurate diagnostic tool and demonstrated substantial clinical utility in the timely detection of C psittaci pneumonia. Future studies with larger sample sizes and prospective designs are warranted to validate these findings.