Activity of Omadacycline in Rat Methicillin-Resistant Staphylococcus aureus Osteomyelitis.

Omadacycline, vancomycin and rifampin as well as rifampin combination therapies were evaluated in an experimental rat model of MRSA osteomyelitis. All treatment groups had less MRSA recovered than saline-treated animals. Emergence of rifampin resistance was observed in 3 of 16 animals with rifampin monotherapy, and none with rifampin combination therapy. After treatment, the median tibial bacterial load was 6.04, 0.1, 4.81 and 5.24 log10 cfu/g for saline-, rifampin-, vancomycin- and omadacycline-treated animals. Omadacycline or vancomycin administered with rifampin yielded no detectable MRSA. Omadacycline, administered with rifampin, deserves evaluation in humans as a potential treatment for osteomyelitis.