Bacterial
osteomyelitis is a major clinical challenge in human and veterinary patients. This
infection is an infrequent but feared complication of
orthopedic surgery and is mainly caused by methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to evaluate the efficacy of
dalbavancin (dosed for either 7 or 14 days) in an MRSA-
osteomyelitis tibial bone model. A total of 39 rats were included in the study. All animals received an inoculum of a clinical strain of MRSA (106 colony-forming units [CFU]) injected into the proximal tibia under
general anesthesia.
Dalbavancin was injected intraperitoneally for 7 or 14 days in 13 animals each; the remaining 13 animals received
saline solution.
After treatment, the animals were sacrificed. Infected tibiae were recovered for histological evaluation and microbiological analysis (MRSA count per gram of bone). Rats that received
dalbavancin showed a statistically significant reduction of MRSA counts compared with the control group: median 0 CFU/g bone (14 days of
dalbavancin) vs. 70 CFU/g bone (7 days of
dalbavancin) and 1600 CFU/g bone (control). Histological evaluation showed typical signs of
osteomyelitis in the control group, whereas there were no signs of bone
infection in 92% of the rats that received 14 days of
dalbavancin. According to this model,
dalbavancin seems to have good efficacy for treating serious Gram-positive bone
infections, including those caused by MRSA.