Examining the effect of preoperative antibiotics for skin grafting surgery on the microbiome in burn patients: a pilot study

Aim: Severely burn injured patients present in an immunocompromised state with loss of skin integrity. Systemic antibiotics are necessary to treat infection in this population, but even small doses may select resistant organisms and alter the host microbiome. Despite this, preoperative antibiotics in burn injury remain debated and their impact on the host microbiome has not been fully elucidated. This work examined the effect of a single preoperative antibiotic dose on the microbiome and clinical outcomes in burn patients. Methods: Patients with burns < 10% total body surface area (TBSA) requiring a single excision and grafting operation were enrolled and randomized to receive a single preoperative dose of cefazolin (ABX) or no antibiotics (no-ABX). Blood samples, wound swabs, and buccal swabs were obtained serially during and after hospitalization to determine bacterial taxonomy characteristics. Graft loss was determined at clinic follow-up. Results: In ABX patients, there were 29 enriched bacterial taxa within wound beds at dressing takedown [log(LDA) ≥ 2, P ≤ 0.05] and greater than 10 bacterial taxa in buccal swabs at follow-up [log(LDA) ≥ 2, P ≤ 0.05]. There was increasing alpha diversity in ABX patients intraoperatively and at dressing takedown. There were no significant differences in graft loss between groups. Extremophile infiltration was noted in oral and wound microbiomes in ABX patients. Conclusion: Though not affected clinically, these data suggest that a single preoperative antibiotic dose significantly impacts the wound and oral microbiome. Innovative approaches to examining the antibiotic impact on the host microbiome of burn patients may help better tailor antibiotic stewardship.