Nosocomial pneumonia likely caused by Stenotrophomonas maltophilia in two patients with polymyositis.

We report two cases of polymyositis (PM) complicated with nosocomial pneumonia probably caused by Stenotrophomonas maltophilia, which was resistant to multiple antimicrobials. In the first case, the chest CT findings and high serum endotoxin level as well as sputum culture results were helpful for the proper diagnosis and the therapy was successful. However the second patient died of a lung abscess in spite of the intensive antibiotic therapy. When PM patients develop pneumonia unresponsive to various antibiotics, a multi-drug-resistant bacteria such as Stenotrophomonas maltophilia should be considered as the pathogen.