Metagenomic next-generation sequencing of radial ultrasound bronchoscopy-guided "cocktail" specimens as an efficient method for the diagnosis of focal pulmonary infections: a randomised study.

Background: To investigate the value of metagenomic next-generation sequencing (mNGS) in the diagnosis of focal pulmonary infections by using radial ultrasound bronchoscopic "cocktail" specimens.

Methods: From March 2019 to May 2020, 90 patients with focal pulmonary infections [locatable by a radial probe endobronchial ultrasound (RP-EBUS)] treated by the Department of Respiratory and Critical Care Medicine at the Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital (Suzhou, China) were randomly allocated to the "cocktail" group, transbronchial brushing (TBBr) group or bronchoalveolar lavage fluid (BALF) group; 30 patients were assigned to each group. Using the extracted material, the diagnostic efficacy of the mNGS test for pathogen detection was compared across the three groups, and the effect of an antibiotic treatment on detection rate was assessed.

Results: The sensitivity of mNGS analysis in cocktail group, TBBr group and BALF group was 90% (27/30), 66.7 (20/30) and 50% (15/30), respectively. The analysis of the sensitivity of the positive test, the detection rate of multiple pathogens, and the effect of antibiotics on the detection rate by mMGS indicated that the "cocktail" group was significantly higher number of samples positive for pathogens than the TBBr group (P<0.05), and the TBBr group was significantly higher number of samples positive for pathogens than the BALF group (P<0.05).

Conclusions: "Cocktail" specimens had high sensitivity in the identification of focal pathogens, and the use of antibiotics had little effect on the results of the mNGS analysis. These clinically valuable results can be used in the diagnosis and treatment of patients with focal pulmonary infections.