Metagenomic next-generation sequencing for the diagnosis of suspected pneumonia in immunocompromised patients

•Polymicrobial pneumonia is common in immunocompromised patients admitted to the ICU.•The diagnostic performance of mNGS for pneumonia depends on pathogen categories.•mNGS is not sensitive enough for the diagnosis of invasive pulmonary aspergillosis.•The performances of mNGS and conventional tests are similar in bacterial and viral pneumonia.•mNGS is most valuable when comprehensive conventional tests are not available.