Topical antimicrobial prophylaxis in colorectal surgery for the prevention of surgical wound infection: a systematic review and meta-analysis.

BACKGROUND: Among the techniques investigated to reduce the risk of surgical wound infection or surgical space infection (SSI) in patients having colorectal surgery are topical application of antimicrobials (antibiotics and antiseptics) to the open wound or immediately after closure. The aim of the present study was to perform a systematic review of the literature on those treatments, with the exception of antibiotic ointments applied to closed skin, which are adequately assessed elsewhere, and a meta-analysis.
METHODS: Only randomized trials of patients having only colorectal surgery were included in this review. Studies were sought in MEDLINE, EMBASE, the Cochrane Register of Controlled Trials, Clinical Trials.gov, and the World Health Organization Internet clinical trials register portal. In addition, reference lists of included studies and other published reviews were screened. Meta-analysis was performed for all included studies and subgroup analyses done for each individual intervention. Risk of bias was assessed for each included study, paying particular attention to the preoperative antibiotic prophylaxis used in each study. Sensitivity analyses were done to investigate heterogeneity of the analyses, excluding those studies with a significant risk of bias issues. Absolute risk reduction (RR) was calculated. The overall quality of the evidence for each individual intervention was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, and was classified as high, moderate, low or very low.
RESULTS: A total of 30 studies are included in this review with 5511 patients, 665 of whom had SSI. The interventions included: 10 studies of gentamicin impregnated sponge or beads wound inlays, 4 studies of chlorhexidine impregnated suture, 11 studies of direct wound lavage or powder application or injection of antibiotics before closure, 4 studies of ionized silver dressing applied to the closed skin, and 1 study of vitamin E oil applied to the open wound. All but one study used preoperative antibiotic prophylaxis in addition to topical procedures, although, in some studies, the systemic antibiotic prophylaxis was not the same between groups or varied significantly from the recommended guidelines. Use of gentamycin sponge did not decrease SSI (RR 0.93, 95% CI 0.75-1.16; low-quality evidence) even after including only the studies of abdominal wounds (RR 1.02, 95% CI 0.80-1.30; low-quality evidence). However, sensitivity analysis excluding studies at high risk of bias decreased the heterogeneity and increased the effect of the prophylaxis for all wounds (RR 0.5, 95% CI 0.33-0.78; low-quality evidence) and for abdominal wounds only (RR 0.38, 95% CI 0.20-0.72; moderate-quality evidence). Chlorhexidine impregnated suture showed no effect on SSI (RR 0.79, 95% CI 0.56-1.10; low-quality evidence) and an increased efficacy after sensitivity analysis (RR 0.42, 95% CI 0.22-0.79; low-quality evidence). Antibiotic lavage showed a significant decrease in SSI (RR 0.45, 95% CI 0.26-0.79; low-quality evidence) which increased after sensitivity analysis (RR 0.33, 95% CI 0.15-0.72; moderate-quality evidence). Application of silver dressing to the closed wound resulted in a decrease of SSI (RR 0.55, 95% CI 0.35-0.85; moderate-quality evidence). The one study of topical vitamin E oil applied to the open wound showed a significant risk reduction (RR 0.22, 95% CI 0.05-0.98; low-quality evidence).
CONCLUSIONS: Each of these interventions appears to be effective in decreasing SSI, but the number of studies for each is small and the quality of evidence is very low to moderate. Within the various outcomes of GRADE assessment, even a moderate classification suggests that further studies may well have very different results.. No randomized trials exist of combinations of two or more of the above interventions to see if there is a combined effect. Future studies should make sure that the antibiotic used preoperatively is uniform within a study and is consistent with the current guidelines. Deviation from this leads to a significant heterogeneity and risk of bias.