Intravenous plus oral antibiotics reduces infections after colorectal surgery

Use of oral antimicrobial prophylaxis with a single oral dose of ornidazole 1 g as an adjunct to intravenous antibiotic prophylaxis results in lower rates of surgical site infection within 30 days following elective colorectal surgery than with placebo, results of a multicentre trial have shown.

“Among adults undergoing elective colorectal surgery, the addition of a single 1-g dose of ornidazole compared with placebo before surgery significantly reduced surgical site infections,” said the researchers, led by Emmanuel Futier, professor in anaesthesia and intensive care at Centre Hospitalier Universitaire de Clermont-Ferrand, Hôpital Estaing, Clermont-Ferrand, France.

Eleven university and nonuniversity hospitals in France participated in this randomized, double-blind, placebo-controlled trial between 25 May 2016 and 8 August 2019. A total of 926 adults (mean age 63 years, 60 percent men) scheduled for elective colorectal surgery were included.

Patients were randomly assigned to receive either a single dose of ornidazole 1 g (n=463) or placebo (n=463) orally 12 hours before surgery in addition to intravenous antimicrobial prophylaxis prior to surgical incision.

Fewer patients in the oral prophylaxis group than those in the placebo group developed a surgical site infection within 30 days after surgery (13 percent vs 22 percent; absolute difference, ‒8.6 percent, 95 percent confidence interval [CI], ‒13.5 to ‒3.8; relative risk, 0.60, 95 percent CI, 0.45‒0.80). [BMJ 2022;379:e071476]

Deep infections were also fewer in the oral prophylaxis group than in the placebo group (4.8 percent vs 8.0 percent; absolute difference, ‒3.2 percent, 95 percent CI, ‒6.4 to ‒0.1). Likewise, the proportion of patients with organ space infections was lower in the oral prophylaxis group compared to the placebo group (5.0 percent vs 8.4 percent; absolute difference, ‒3.4 percent, 95 percent CI, ‒6.7 to ‒0.2).

In addition, more patients in the placebo group had major postoperative complications relative to those in the oral prophylaxis group (13.6 percent vs 9.1 percent; absolute difference, ‒4.5 percent, 95 percent CI, ‒8.6 to ‒0.5).

Anastomotic leakage

“The overall incidence of surgical site infection in our study (17.3 percent) was slightly higher than hypothesized but consistent with rates reported in previous trials (ranging from 7 percent to 26 percent),” the researchers said. [N Engl J Med 2010;363:1038-1049; N Engl J Med 2006;355:2640-2651; Lancet 2019;394:840-848; N Engl J Med 2010;362:18-26]

“A possible explanation is the 35.5-percent proportion of rectal procedures in this study. Rectal resection is associated with a higher risk of anastomotic leakage and surgical site infections than would be expected after intraperitoneal colon resection,” they added. [Lancet 2005;365:1718-1726]

Previous meta-analysis of randomized trials also revealed lower rates of surgical site infections with the use of oral antibiotics, whether alone or in combination with mechanical bowel preparation. [JAMA Netw Open 2018;1:e183226; Cochrane Database Syst Rev 2014;CD001181:CD001181; Ann Surg 2019;270:43-58]

In another trial involving patients who did not receive bowel preparation, oral antibiotics reduced surgical infections, but this study did not include rectal surgery. [Lancet Gastroenterol Hepatol 2020;5:729-738]

“In our study, the effects of oral prophylaxis in the prespecified subgroup analysis did not differ between the groups who underwent colonic surgery and rectal surgery,” the researchers said. “The number of patients who had rectal surgery was, however, too low to draw definite conclusions.” [Lancet Infect Dis 2016;16:e276-287; J Am Coll Surg 2017;224:59-74]