Tropheryma whipplei detection by targeted next-generation sequencing in bronchoalveolar lavage fluid: a retrospective study

The purpose of this study was to compile the traits of individuals who tested positive for T. whipplei through targeted next-generation sequencing (tNGS), thereby improving awareness and comprehension of this rare pathogen. A retrospective analysis was performed on individuals with T. whipplei identified in 848 BALF samples, detected by tNGS from 21 September 2022 to 1 March 2024 at The First Hospital of Changsha. Data regarding clinical features, laboratory data, and CT images were gathered for evaluation. Forty-three BALF samples from forty-four (44/848, 5.2%) patients were positive for T. whipplei (one patient was excluded due to incomplete data). Twenty-eight patients were male with an average age of 46.9 years. The main symptoms included cough(38/43), expectoration(34/43), dyspnea(15/43),fever(14/43), hemoptysis/bloody sputum(5/43), myalgia(4/43), fatigue(2/43), vomiting(3/43), abdominal pain (2/43), and headache (2/43). Chronic liver disease (including fatty liver, chronic hepatitis C and chronic hepatitis B) was the most common comorbidity ( n = 13, 30.2%), followed by chronic lung disease ( n = 8, 18.6%). The levels of erythrocyte sedimentation rate (ESR), and lactate dehydrogenase (LDH) were significantly higher in the pneumonia group compared to the non-pneumonia group. Conversely, the ages were significantly lower in the pneumonia group ( P < 0.05). T. whipplei was the exclusive pathogen in 6 samples, while Epstein-Barr virus was the most frequently detected pathogen, followed by Haemophilus influenzae . The most prevalent finding on chest CT scans was lung nodules (18/43, 41.9%), which included fourteen solid nodules and five ground-glass nodules (three cases of calcified nodules attributed to pulmonary tuberculosis were excluded). In conclusion, our study suggests that T. whipplei may play a pathogenic role in various pulmonary diseases, warranting clinical attention during routine clinical practice. The application of tNGS technology can effectively improve the detection rate of rare pathogens, potentially providing references for clinical decision-making.