Efficacy of dalbavancin in the treatment of MRSA rat sternal osteomyelitis with mediastinitis

Dalbavancin, a semi-synthetic lipoglycopeptide, is characterized by a long plasma half-life, which allows weekly dosing. Dalbavancin may be a good treatment option for patients with deep sternal wound infections owing to its improved pharmacokinetic profile and antibacterial activity compared with currently used antibiotics. Here we evaluated the efficacy of 7 or 14 days of treatment with dalbavancin, compared with vancomycin and with saline, in reducing sternal bone MRSA counts in a rat Staphylococcus aureus deep sternal wound infection model. A mid-sternal wound was surgically induced in anaesthetized rats. A clinical strain of MRSA was injected into the sternum to establish infection. Rats were treated intraperitoneally for 7 or 14 days with dalbavancin, vancomycin or saline. The number of cfu per gram of sternum or spleen tissue was determined using viable counts. The antibacterial efficacy was determined by the reduction in bacterial counts per gram of sternum or spleen tissue in each treatment group. Treatment with dalbavancin was superior to treatment with saline for 7 days (0.75 log reduction in bone cfu) or 14 days (> 3 log reduction in bone cfu) and similar to treatment with vancomycin. Additionally, dalbavancin was also effective in reducing systemic dissemination of MRSA. Dalbavancin is effective in the treatment of MRSA rat sternal osteomyelitis.