Data indicate that overuse of antibiotics is a main driver of antibiotic resistance, with every exposure to antibiotics creating a selection event with each patient’s microbiome, in turn, giving rise to more resistant bacteria, says David M. Hill, PharmD. Although current international burn injury guidelines do not support prophylactic antibiotics for patients awaiting excision, current surgical guidelines focusing on antimicrobial prophylaxis classify thermal injury under a general plastics procedure umbrella, requiring significant evidential extrapolation to apply to patients with burn injuries. And while thermal injuries admitted without significant delay rarely present with infection, according to Dr. Hill, prophylactic antibiotics are often prescribed in this setting.

Preop Vs Non-Preop Antibiotics

For a study published in Burns, Dr. Hill and colleagues sought to determine the utility of preoperative antibiotics in patients with less severe burns. “This was a 3-year retrospective, non-inferiority study comparing the incidence of postoperative infectious-related complications in patients with thermal injuries covering less than 20% of total body surface area (TBSA) who either did or did not receive prophylactic antibiotics prior to undergoing wound excision,” explains Dr. Hill. The study team defined success as lack of graft loss, bacteremia, or surgical site infection among the 100 patients who underwent 133 operations (74% male; median age, 41; median TBSA, 5%).

With observed success rates of 81.7% for patients who received preoperative antibiotics and 84.3% for those who did not and one clinical significant bacteremia in each group, Dr. Hill says, “There is little evidence supporting use of preoperative antibiotics in small burn injuries presenting without active infection. Routinely prescribing antibiotics without regard for presence of active infection may be more harmful than helpful.” Indeed, withholding preoperative antibiotics was found to be non-inferior to prescribing such therapy, with a percent difference of 2.6 (95% confidence interval, -10.4, 15.6). Infection-related complications were no more likely to occur in patients who were not prescribed antibiotics than in patients who did. The composite of bacteremia, lack of graft loss, and surgical site infection—as well as the confidence intervals for each of these components individually—was found to not breach the a priori non-inferiority margin, explains Dr. Hill (Figure). “In other words, avoiding prophylactic antibiotics did not result in worse outcomes,” he adds. “While not statistically significant, there were slight procedural difference noted in the two groups. However, a generalized linear model was utilized to ensure none of these variables confounded the findings (Table). The regression demonstrated that the variables did not impact complication incidence, neither individually nor together.”

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Early & Appropriate Intervention Is Key

Dr. Hill notes that while the study team didn’t specifically assess the deleterious effects of antibiotics on the flora, numerous studies have demonstrated these effects. “Every effort should be given to avoid infection without prophylactic antibiotics,” he says. “Wounds should be afforded prompt attention with frequent debridement. Those without significant experience caring for burn injuries should seek advice from an experienced clinician or promptly transfer the patient. Early attention and treatment decisions have substantial long-term implications.”

Looking to the future, Dr. Hill is hopeful that research will continue to focus on strategies for preventing infection and surgery among patients with burn injuries all together. “More studies are needed focusing on the microbiome in patients with burn injuries treated in burn centers,” he notes. “We are not even able to identify and classify the vast majority of flora within or around us, let alone understand their functions.” In the meantime, though, the current study suggests that withholding preoperative systemic antibiotics in patients with less than 20% TBSA burns and without active wound infections can preserve unneeded antimicrobial exposure without increasing infection-related complication risks.