Abstract
Background: To evaluate the diagnostic value of metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) in immunocompromised patients for the diagnosis of suspected pneumonia in comparation to that of conventional microbiological tests (CMTs).Methods: Sixty-nine immunocompromised patients with suspected pneumonia received both CMTs and mNGS of BALF were analyzed retrospectively. The diagnostic value was compared between CMTs and mNGS, using the clinical composite diagnosis as the reference standard. Results: Sixty patients were diagnosed of pneumonia including fifty-two patients with identified pathogens and eight patients with probable pathogens. The overall detection rate of mNGS for pathogens were higher than that of CMTs. However, a comparable diagnostic accuracy of mNGS and CMTs were found for bacterial and viral infections. mNGS exhibited a higher diagnostic accuracy for fungal detection than CMTs (78% vs. 54%, P＜0.05), which mainly because of the high sensitivity of mNGS in patients with Pneumocystis jirovecii pneumonia (PJP) (100% vs. 28%, P＜0.05). Among fifty-two patients with definite pathogens, nineteen patients (37%) were identified as pulmonary mixed infection, mNGS test showed a higher detection rate and broader spectrum for pathogen detection than that of CMTs in mixed infection. Moreover, Pneumocystis jirovecii was the most common pathogen in mix infection and mNGS have identified much more co-pathogens of PJP than CMTs.Conclusions: mNGS of BALF improved the microbial detection rate of pathogens and exhibited remarkable advantages in detecting PJP and identifying mixed infections in immunocompromised patients.
Evaluating the diagnostic accuracy of the Xpert MTB/RIF assay on bronchoalveolar lavage fluid: A retrospective study
