Topical vancomycin applied on closure of the sternotomy wound does not prevent high levels of systemic vancomycin.

OBJECTIVE Vancomycin is effective in reducing the risk of mediastinits and topical vancomycin has been hypothesised to give high local dose concentrations while avoiding high systemic levels, thus avoiding the risk of bacterial resistance to this second-line antibiotic. However, this theory has never been tested and the degree to which vancomycin is absorbed systemically is unknown. METHODS Fourteen patients undergoing elective coronary artery bypass grafts (CABG) received 500mg of topical vancomycin prior to sternotomy closure. Serum samples were taken at 30, 60, 120, 180 and 720min post-operatively. In addition, samples were taken from the drain bottles and urine samples taken daily for 5 days. Vancomycin levels were measured by fluorescence polarisation immunoassay, using the reverse dilution method to give a detection limit of 0.8mg/l. RESULTS Vancomycin was detected in almost all serum samples. Peak concentration was at 30min and the mean value was 2.96mg/l (range, 0.99-5.00mg/l). This mean fell to 1.32mg/l at 6h. Of the 500mg of vancomycin applied, a mean of only 8.8mg was found to have been lost into the drain bottles in the first 24h (range, 0.17-12.5mg). When 5 consecutive days of urine collection was achieved, a mean of 151mg of vancomycin was excreted (range, 40-195mg) and vancomycin was detectable in the urine till day 5. The mean concentration of vancomycin in the urine was maximal on day 1 and was 24.4mg/l (range, 4.49-44.98mg/l). CONCLUSIONS Topical vancomycin causes significant systemic concentrations in the 6h post-surgery and can be detected in the urine for up to 5 days post-surgery.