Clinical value of metagenomic next-generation sequencing in diagnosis of Coxiella burnetii infection.

Background: Metagenomic next-generation sequencing (mNGS) is a new pathogen detection technique, but the current experience of clinical application in Coxiella burnetii infection is relatively limited. This study aimed to investigate the clinical application value of mNGS in diagnosis of Coxiella burnetii infection.

Methods: We conducted a retrospective study that included patients with Coxiella burnetii infection detected by mNGS from December 2018 to August 2024. Their clinical information and mNGS test results were retrieved for analysis.

Results: A total of 70 patients with Coxiella burnetii infection were included in this study. The mean age of these patients was 43.5 years and the common clinical manifestations were fever (67/70, 95.7%), followed by headache (43/70, 61.4%), weakness (36/70, 51.4%), and muscle and joint pain (27/70, 38.6%). The mean length of hospitalization was five days. 92.9% (65/70) patients were discharged with improvement, and one patient died. The median duration of fever for these patients was seven days. Most patients temperatures returned to normal within 2-3 days after receiving targeted antibiotic therapy. No correlation was observed between the duration of fever and the reads of mNGS in febrile patients. The specimens tested by mNGS were mainly blood specimens. The reads of mNGS detected fluctuated from one to 826, with the range of one to 50 being the most frequent. 43 (61.4%) samples of mNGS detected only Coxiella burnetii. Pathogens detected along with Coxiella burnetii include viruses, bacteria, and fungi. None of the 63 patients followed up for six months had clinical manifestations of chronic Q fever.

Conclusions: Q fever is a disseminated infectious disease that deserves attention for its nonspecific clinical symptoms. mNGS emerges as a powerful novel tool for pathogen detection, demonstrating significant value in diagnosing Q fever, particularly in where conventional serological and PCR testing is unavailable or inconclusive.