Inadequate antimicrobial prophylaxis during surgery: a study of beta-lactam levels during burn debridement

Objectives: To determine how long single-dose prophylactic antibiotic regimens for burns surgery maintained plasma concentrations above the MICs for target organisms during surgery. Patients and methods: We monitored antibiotic plasma concentrations in 12 patients (mean+SD 43+ 12 % total burn surface area) throughout debridement surgery after administration of the standard pro-phylactic antibiotic dosing regimens of either 1 g of intravenous cefalotin or 4.5 g of intravenous piper-acillin/tazobactam. Results: The eschar debridement and grafting procedures ranged in duration from 2.25 to over 8.5 h. The duration of total plasma cefalotin concentration above an MIC of 0.2 mg/L for Staphylococcus aureus was 6.49+ 2.85 h, whereas the mean duration of total plasma piperacillin concentration above an MIC of 64 mg/L for Pseudomonas aeruginosa was only 1.15+ 0.59 h. None of the patients dosed with piperacillin/tazobactam was adequately protected for the duration of their surgery and adequate prophylaxis was only evident in four of the nine patients administered cefalotin. Conclusions: These results suggest a need to review antibiotic prophylaxis dosage regimens for burns surgery and the adoption of regimens that will minimize the risk of infection in this high-risk patient group. It is suggested that the antibiotic prophylaxis guideline for burn debridement surgery be modi-fied to include re-dosing or a continuous infusion of b-lactam antibiotics