2022 Volume 71 Issue 4 Pages 748-753
A female in her 60s suffered from chronic osteomyelitis of the tibia after injury resulting in an open fracture of the right lower leg. She was treated with various antibacterials and by curettage of the lesion and artificial bone implantation after indwelling cement beads containing antibacterials five times over four years and six months. The patient was admitted to our hospital for radical cure of her chronic osteomyelitis. Staphylococcus capitis subspecies urealyticus was isolated from the lesion on day 45 of hospitalization. Antibacterial susceptibility testing based on the agar dilution method and/or broth microdilution method showed high minimum inhibitory concentrations (MICs) of vancomycin (VCM), teicoplanin (TEIC), and daptomycin (DAP) (4, 64, and 2 μg/mL, respectively). The patient had no history of DAP administration, but the bacterial isolate was not susceptible to DAP. With linezolid administration since day 76, her fever was relieved, the white blood cell count declined, and the macroscopic findings of the wound were improved. The periapical culture was confirmed to be negative for the bacterium on day 79, and the patient was discharged on day 133. In this patient, VCM-containing artificial bone implantation was performed two years and two months after the injury. A long-term exposure to VCM-containing artificial bone implantation might have selected for these bacteria with low susceptibility to VCM, displaying thickened cell walls, which might have resulted in the reduced susceptibility to DAP. When a bacterium with reduced susceptibility to VCM or TEIC was isolated from a patient with a history of long topical exposure to these antibacterials as in this case, it would be important to predict the efficacy of DAP before administration, even if the patient has no history of DAP administration.
