Mechanical bowel prep, oral antibiotics best prophylaxis before colorectal surgery

Last Updated: 2018-10-23

By Will Boggs MD

NEW YORK (Reuters Health) - Mechanical bowel preparation and oral antibiotics before elective colorectal surgery is the best strategy for preventing surgical site infections (SSI), according to a network meta-analysis.

"In the era of evidence-based medicine, we should acknowledge the growing body of evidence that supports prophylaxis with oral antibiotics for elective colorectal operations," Dr. James W. T. Toh from Sydney Medical School at the University of Sydney told Reuters Health by email.

The American Society for Enhanced Recovery and the Perioperative Quality Initiative endorse the routine use of combined isosmotic mechanical bowel preparation (MBP) with oral antibiotics (OAB) before elective colorectal surgery.

But there has been a lack of consensus among international guidelines, with some recommending against routine mechanical bowel preparation, Dr. Toh and colleagues note in JAMA Network Open, online October 12.

The team used data from 38 randomized controlled trials, including 8,458 patients, to compare SSI rates after elective colorectal surgery in their network analysis of four regimens: MBP with OAB, OAB only, MBP only, or no preparation.

MBP with OAB was associated with a 29% reduction in the odds of developing SSI compared with MBP only, and a 40% reduction compared with no preparation, both significant findings.

SSI rates did not differ significantly between MBP only versus no preparation or between MBP with OAB versus OAB only.

Three different analyses showed that MBP with OAB had the highest probability of having the lowest total postoperative SSI rate, followed by OAB only, MBP only, and no preparation.

For incisional SSI, the ranking (from highest to lowest probability of having the lowest SSI rate) was MBP with OAB, OAB only, no preparation, and MBP only, whereas for organ/space SSI, the ranking was OAB only, MBP with OAB, MBP only, and no preparation.

The rates of anastomotic leak, mortality, readmissions/re-operations, urinary tract infection and pulmonary complications did not differ between the four approaches.

"In a recent international study of colorectal surgeons, less than 10% stated that they used oral antibiotics with or without bowel preparation," Dr. Toh said. "This study showed that patients should be prescribed oral antibiotics and mechanical bowel preparation prior to elective colorectal surgery to reduce their risk of infectious complications including surgical site infections."

"This does not replace intravenous antibiotics at the time of induction of anesthesia, which should be routinely administered," he said.

Dr. E. Patchen Dellinger of the University of Washington, in Seattle, who wrote an accompanying editorial, told Reuters Health by email, "None of the results were surprising. Toh and colleagues simply provided yet another example of what has been clear in the literature for years now. Mechanical prep alone does not benefit the patient in any way. Oral antibiotics plus mechanical prep clinically and statistically benefit patients significantly. Oral antibiotics without mechanical prep might benefit patients, but we do not have enough data and a trial asking that specific question would be valuable."

"All patients having scheduled colorectal surgery should have both a mechanical prep and preoperative oral antibiotics (of course, in addition to intravenous antibiotics in the O.R.), and no patient should be subjected to mechanical prep without oral antibiotics!" he said. "This is yet another example of how easy it is to misinterpret data to fit one's own habits and how long it takes for solid, prospective, randomized evidence to actually get into clinical practice."

Tessa Mulder of the University Medical Center Utrecht in The Netherlands told Reuters Health by email, "In most Dutch hospitals, patients do not receive any kind of bowel preparation before colorectal surgery, though antibiotic bowel preparation was implemented as standard of care in one Dutch teaching hospital."

"In a study we published last week (https://bit.ly/2PgkoP7), we analyzed the effectiveness of implementation of antibiotic bowel preparation for all patients who underwent elective colorectal surgery," said Mulder, who was not involved in the meta-analysis. "In this study, conducted in a setting without routine administration of MBP, implementation of antibiotic bowel preparation resulted in a reduction in deep SSI rate of more than 40%."

"Nevertheless, we need additional (pragmatic) studies to confirm these findings," she said. "Confirming the beneficial effects of oral antibiotics without simultaneous mechanical cleansing would not only implicate a reduction in costs, but more importantly, also a reduced burden for the patient."

Dr. Richard L. Nelson of the University of Illinois Chicago School of Public Health, who has published numerous papers on oral antibiotics with or without MBP before colorectal surgery, told Reuters Health by email, "Every study but one got intravenous antibiotics, which muddies the waters a bit."

"Oral plus IV (antibiotics) without a prep might be more beneficial than IV alone even without an MBP, based upon this study (along with the new kids on the block: topical antibiotics and probiotics), but a clearer answer should be available in the next year or two," said Dr. Nelson, who also was not involved in the new study. "This is really the last great controversy in prevention of SSI in colorectal surgery."

SOURCE: https://bit.ly/2D1qD3s and https://bit.ly/2R7E9Ww

JAMA Netw Open 2018.