[A rare cause of catheter-related bacteremia: Rhizobium radiobacter]

Rhizobium spp. (R. radiobacter, R. rhizogenes, R. rubi, R. vitis) are aerobic, motile, non-spore forming, oxidase-positive, gram-negative bacilli. Although they are mostly plant pathogens, R. radiobacter may cause human infections. The aim of this report was to present a case of R. radiobacter bacteremia treated with levofloxacin. Twenty-seven year old male patient had fever after receiving chemotherapy due to osteosarcoma. The infection focus could not be detected in the initial physical examination. Blood cultures were obtained from peripheral veins and central catheter and levofloxacin (500 mg/day) was started as empirical therapy. His fever resolved on the next day. Meanwhile cultures of blood (Bact/Alert automated systems, bioMerieux, Durham, NC) obtained from peripheral veins and central catheters yielded bacteria which were identified as R. radiobacter by VITEK 2 (bioMerieux Inc, Mercy L'etoil, France). The strain was resistant to amikacin and sensitive to ceftazidime, ciprofloxacin, imipenem, meropenem and piperacillin/tazobactam. The patient was diagnosed as catheter-related bacteremia and the treatment was continued for 14 days. His catheter was not removed since subsequent cultures did not reveal any bacterial growth. In conclusion this case suggests that R. radiobacter may cause infections especially in immunocompromised patients with catheters or prosthetic devices. To our knowledge this is the first R. radiobacter case reported from Turkey and the first case of R. radiobacter bacteremia reported to be treated with levofloxacin in the literature.