Qi Chen,1 Bo Gao,2 Wei Guo,1 Hao Liu,3 Jun Guo1,2 

1Department of Geriatrics, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, Beijing, 102218, People’s Republic of China; 2Department of Respiratory and Critical Care Medicine, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, Beijing, 102218, People’s Republic of China; 3Department of Pathology, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, Beijing, 102218, People’s Republic of China

Correspondence: Jun Guo, Department of Geriatrics, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine, Tsinghua University, 168 Litang Road, Changping District, Beijing, People’s Republic of China, Tel +8613681573493, Email junguo_med@tsinghua.edu.cn

Introduction: Tropheryma whipplei (TW) can cause various infections that are relatively rare worldwide. With the development of molecular biology, the ability to detect TW has increased in recent years. However, its significance in lower respiratory tract samples remains unclear.
Patients and Methods: We collected the clinical data of 5 patients admitted to a tertiary care hospital in Beijing with TW detected by bronchoalveolar lavage fluid (BALF) mNGS and reviewed all case reports of TW-related pneumonia in China (up to November 2024) to analyse the features of this disease among Chinese patients.
Results: A total of 41 articles reporting 55 cases were identified. Fifty-two (94.5%) patients had respiratory symptoms. Fifteen (27.3%) patients developed severe pneumonia. Confirmation of TW infection was achieved through methods including the assessment of TW reads and relative abundance (63.6%), empirical treatment (18.2%), lung biopsy histopathology (14.5%), and qPCR confirmation (3.6%). Fifty (90.9%) patients received antibiotic therapy. Fifty-one (92.7%) patients had a good prognosis.
Conclusion: TW can enter the lower respiratory tract through multiple routes. When TW sequences are detected in lower respiratory tract samples, it is important to consider not only the read and relative abundance but also histopathological findings such as interstitial pneumonia and the presence of PAS- or PASM-positive bacilli within foamy macrophages as they can aid in diagnosing TW infection. MDT discussions and empirical antibiotic therapy targeting TW are viable options when a patient’s condition deteriorates. Microbiological testing of saliva, gastric fluid, blood, and faeces may help clarify the source of TW.

Keywords: Tropheryma whipplei, lower respiratory tract, metagenomic next-generation sequencing, bronchoalveolar lavage fluid, pneumonia