Pneumonia with BALF Detection of Tropheryma whipplei and Chlamydia psittaci by Targeted Next-Generation Sequencing: A Case Report.

BACKGROUND: Tropheryma whipplei (TW), a Gram-positive bacterium, is the etiologic agent of Whipple's disease, a chronic and systemic condition that primarily involves the gastrointestinal tract. Chlamydia psittaci (C. psittaci) is a zoonotic pathogen that primarily leads to psittacosis after bird exposure. Both are fastidious organisms that are difficult to culture, and documented co-detection in pulmonary infection is relatively rare. We describe a pneumonia case in which both TW and C. psittaci were identified by targeted next-generation sequencing (tNGS).

CASE PRESENTATION: A 69-year-old male farmer presented with a 5-day history of high fever. After a 3-day course of oseltamivir for presumed influenza failed, he was hospitalized with persistent fever. Chest computed tomography (CT) showed patchy opacities with pleural thickening. Initial moxifloxacin therapy was ineffective. The tNGS of bronchoalveolar lavage fluid (BALF) detected TW and C. psittaci. Antibacterial therapy was switched to intravenous ceftriaxone combined with oral doxycycline. The patient's fever subsided rapidly, inflammatory markers declined, and subsequent CT scans over six months demonstrated progressive radiographic resolution.

CONCLUSION: This case illustrates that tNGS can provide early detection of fastidious pathogens such as TW and C. psittaci when conventional testing is unrevealing, thereby guiding targeted antimicrobial therapy and contributing to a favorable clinical outcome. A causal role for both organisms is supported by the clinical and radiographic response but would require orthogonal confirmation to be considered definitive.