Choice of intravenous antibiotic prophylaxis for colorectal surgery does matter.

Background: The Surgical Care Improvement Program endorses mandatory compliance with approved intravenous prophylactic antibiotics; however, oral antibiotics are optional. We hypothesized that surgical site infection (SSI) rates may vary depending on the choice of antibiotic prophylaxis.

Study Design: A retrospective cohort study of elective colorectal procedures using Veterans Affairs Surgical Quality Improvement Program (VASQIP) and SSI outcomes data was linked to the Office of Informatics and Analytics (OIA) and Pharmacy Benefits Management (PBM) antibiotic data from 2005 to 2009. Surgical site infection rates by type of IV antibiotic agent alone (IV) or in combination with oral antibiotic (IV + OA) were determined. Generalized estimating equations were used to examine the association between type of antibiotic prophylaxis and SSI for the entire cohort and stratified by use of oral antibiotics.

Results: After 5,750 elective colorectal procedures, 709 SSIs (12.3%) developed within 30 days. Oral antibiotic + IV (n = 2,426) had a lower SSI rate than IV alone (n = 3,324) (6.3% vs 16.7%, p < 0.0001). There was a significant difference in the SSI rate based on type of preoperative IV antibiotic given (p ≤ 0.0001). Generalized estimating equations adjusting for significant covariates of age, body mass index, procedure work relative value units, and operation duration demonstrated an independent protective effect of oral antibiotics (odds ratio [OR] 0.37, 95% CI 0.29 to 0.46), as well as increased rates of SSI associated with ampicillin/sulbactam (OR 2.21, 95% CI 1.37 to 3.56) and second generation cephalosporins (cefoxitin, OR 2.50, 95% CI 1.83 to 3.42; cefotetan, OR 2.70, 95% CI 1.72 to 4.22) when compared with first generation cephalosporin/metronidazole.

Conclusions: The choice of IV antibiotic was related to the SSI rate; however, oral antibiotics were associated with reduced SSI rate for every antibiotic class.