A case of Moraxella osloensis bacteremia presumably identified using common microbiological testing methods

Abstract

Moraxella osloensis is a gram-negative coccobacillus commonly present in the human upper respiratory tract. However, it rarely causes infection, and reports of bacteremia are limited. Here, we report a case of M. osloensis bacteremia in an 87-year-old man undergoing biliary stent placement for lower bile duct cancer. The patient visited our hospital with a fever of 38.0°C, chills, and abdominal pain. He had underlying lower bile duct cancer, and a CT scan revealed a dislocated biliary stent. Endoscopic retrograde biliary drainage (ERBD) was performed, and the biliary stent was repositioned before admission. Two blood culture sets were obtained at the time of admission, and treatment with tazobactam/piperacillin (TAZ/PIPC) was initiated. Forty-eight hours later, gram-variant bacteria were detected in one aerobic bottle out of two sets of four blood cultures, and were identified as M. osloensis. After hospitalization, the patient’s symptoms improved, and he was discharged on the fifth day. This case involved M. osloensis bacteremia triggered by biliary stent displacement, and although it is a rare bacterium, it suggests that it is a causative bacterium that should be differentiated in immunocompromised patients and device-related infections.