Oral Antibiotics Might Combat Surgical Site Infection After Left Colon, Rectal Cancer Resection

Combining mechanical bowel preparation and oral antibiotics may reduce the likelihood of surgical site infection after resection of left colon and rectal cancer

medwireNews: A review published in JAMA Surgery suggests that surgical site infection (SSI) after left colon or rectal cancer resection may be significantly less likely if oral antibiotics are added to a mechanical bowel preparation (MBP).

“Because there have been no contemporaneous randomized clinical trials evaluating the use of oral antibiotics and MBP, to our knowledge, it may be time for a trial to demonstrate whether the findings in our work and other recent studies are truly attributable to use of oral antibiotics and MBP”, say Samir Awad, from the Michael E DeBakey Veterans Affairs Medical Center in Houston, Texas, USA, and co-authors.

“Future work is also needed to understand whether the benefits of oral antibiotics and MBP are also present for patients undergoing right colon resections”, they write, recommending that “[u]ntil such data become available, clinicians should consider using oral antibiotics and MBP for all patients undergoing left-sided colorectal cancer resections.”

The researchers report findings from 89 patients who underwent surgery between 2013 and 2016 at one institution; 49 underwent surgery before August 2015 and were given MBP alone, consisting of neomycin sulphate, metronidazole hydrochloride and magnesium citrate, while the 40 patients treated after this point also received oral antibiotics.

The overall SSI rate was 8% for patients given MBP plus oral antibiotics versus 27% for those given MBP alone, a significant difference.

None of the patients who received MBP plus oral antibiotics developed a deep or organ space SSI or experienced anastomotic leak, whereas 18% of patients given MBP only had an organ space SSI and 10% anastomotic leak, although only the difference in the rate of organ space SSI reached statistical significance.

Nevertheless, multivariable analysis confirmed that both receipt of oral antibiotics plus MBP and a minimally invasive surgical procedure significantly and independently predicted a lower risk of SSI, with odds ratios of 0.11 and 0.22, respectively.

Time to receipt of adjuvant therapy did not significantly differ between the patients given oral antibiotics plus MBP and those given MBP alone (median 72 versus 60 days), despite a significantly reduced rate of SSIs among adjuvant-treated patients given oral antibiotics versus MBP alone (0 vs 29%).

“Delays to adjuvant therapy for the patients who received oral antibiotics and MBP were attributed to poor healing of perineal wounds after abdominoperineal resection without evidence of infection and early ileostomy reversals,” remark the authors, noting that scheduling and patient attendance at the clinic may also have caused delays.

“Further efforts to improve postoperative outcomes after colorectal cancer resections are needed to increase the number of patients receiving timely adjuvant therapy,” they emphasize.

While acknowledging that the study was retrospective and the sample size was small, Marc Basson, from the University of North Dakota in Grand Forks, USA, believes the current findings confirm reports going back to 1973 showing a reduced risk of SSI after left colon resection with oral antibiotics.

“Surgical site infections produce substantial morbidity among our patients”, he writes in an accompanying comment.

And the commentator concludes: “Given all the efforts that we have made to reduce infection rates by ineffective methods such as mandating compliance with the Surgical Care Improvement Project and experimenting with varieties of decontamination and skin preparation techniques, perhaps it is time to stop studying this issue and simply (re)adopt the practice of oral antibiotic use more universally, at least for elective surgery on the mechanically prepared left colon.”

References

Vo E, Massarweh NN, Chai CY, et al. Association of the addition of oral antibiotics to mechanical bowel preparation for left colon and rectal cancer resections with reduction of surgical site infections. JAMA Surg; Advance online publication 18 October 2017. doi:10.1001/jamasurg.2017.3827

Basson MD. Oral antibiotics for colon surgery. The questions remain the same, as do the answers. JAMA Surg; Advance online publication 18 October 2017. doi:10.1001/jamasurg.2017.3843

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