Topical versus systemic vancomycin for deep sternal wound infection caused by methicillin-resistant Staphylococcus aureus in a rodent experimental model

Abstract

In 37 Wistar albino rats, we investigated the effects of topical vancomycin on deep sternal wound infection caused by methicillin-resistant Staphylococcus aureus. Partial median sternotomy was performed under sterile conditions. Group I (n=6) was the sham, and group II (n=7) was the control. Group III (n=8) received topical vancomycin, group IV (n=8) received systemic vancomycin, and group V (n=8) received topical and systemic vancomycin (combined). Rats in groups II through V were inoculated with 0.5 mL × 108 CFU/mL methicillin-resistant S. aureus in the mediastinum and sternum. No medication was given to groups I and II. Twenty-four hours after surgery, 40 mg/kg/day vancomycin was given topically in group III; systemically in group IV; and topically and systemically in group V. After 7 days, smear samples from the mediastinum and tissue cultures from the sternum were obtained. We found 5.00 ± 0 CFU/mL microorganisms in the mediastinum in group II, 1.90 ± 1.70 in group III, 3.33 ± 0.48 in group IV, and 1.70 ± 1.08 in group V. The quantity of microorganisms per gram of tissue in the sternum was 7.36 ± 0.23 in group II, 6.01 ± 0.33 in group III, 5.81 ± 0.81 in group IV, and 3.99 ± 2.47 in group V. The quantity of microorganisms was less in the 3 treatment groups than in the control group (P <0.05). We conclude that topical plus systemic vancomycin treatment might be more effective in patients with deep sternal wound infections caused by methicillin-resistant S. aureus. © 2006 by the Texas Heart® Institute.