RECURRENT METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS OSTEOMYELITIS -COMBINATION ANTIBIOTIC-THERAPY WITH EVALUATION BY SERUM BACTERICIDAL TITERS

OBJECTIVE: TO report on a patient with recurrent methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis and bacteremia successfull y treated with combination antibiotic therapy. CASE SUMMARY: Two sets of blood cultures from a 55-year-old man with fever, malaise, and low back pain grew MRSA. Radiologic studies of the spine showed bony chang es consistent with osteomyelitis. Soon after completing 6 weeks of van comycin, the patient experienced a recurrence of back pain. Laboratory values included an increase in the sedimentation rate to 53 mm/h and positive blood cultures for MRSA. Vancomycin, gentamicin, and rifampin were administered for 8 weeks. Serum inhibitory and bactericidal tite rs were more than 1:1024 for both the peak and trough concentrations, Radiologic studies of the spine showed healing osteomyelitis. Two year s after completion of antibiotic therapy, the infection has not recurr ed. DISCUSSION: Antibiotic therapy alone was attempted because the pat ient was considered a risky surgical candidate, Serum inhibitory and b actericidal titers documented the high in vivo activity of the vancomy cin, gentamicin, and rifampin combination. Initiation of vancomycin th erapy led to disappearance of the fever and back pain. Cure was docume nted by sustained normalization of the erythrocyte sedimentation rate and radiologic evidence of healing. CONCLUSIONS: Combination antibioti c therapy with vancomycin, rifampin, and low-dose gentamicin(1 mg/kg q 12h) may be useful for deep-seated tissue infection caused by MRSA.