Methylobacterium species are heterotrophic and fastidious Gram-negative bacilli that can be opportunistic pathogens in immunocompromised patients. These species form pink-pigmented colonies on agar plates and have been frequently isolated from tap water in hospitals. Herein, we describe a case of vascular access-related bloodstream infection caused by Methylobacterium radiotolerans in an 82-year-old man who was undergoing hemodialysis and had an implanted permanent pacemaker. Gram-negative rods cultured from his peripheral blood after incubation for 7 days were identified as M. radiotolerans by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing. The patient was treated with meropenem and daptomycin for 8 days, and levofloxacin was subsequently given orally for 6 days. However, eleven days after completion of the treatment, the patient developed another febrile episode, and the vascular access line blood and his peripheral blood also grew M. radiotolerans. Meropenem and rifampicin were administered and the vascular access line was removed and replaced. Subsequently, oral levofloxacin and rifampicin treatment was maintained for 8 weeks and the patient recovered without removal of the permanent pacemaker. M. radiotolerans grew slowly in blood culture, and the isolate showed optimal growth on Reasoner's 2 Agar (R2A). To our knowledge, this is the first report of a hemodialysis vascular access-related bloodstream infection caused by M. radiotolerans in Japan. Our experience suggests that clinicians should be aware of the possibility of vascular access infection caused by M. radiotolerans.
Keywords: Hemodialysis; Heterotrophic bacteria; Methylobacterium radiotolerans; Reasoner's 2 agar; Vascular access infection.
Copyright © 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.