Antibiotic Prophylaxis With Trimethoprim/Sulfamethoxazole Instead of Cloxacillin/Cefotaxime Increases Inguinal Surgical Site Infection Rate After Lower Extremity Revascularization.

Due to the consistently high proportion of surgical site infections (SSI) after vascular surgery, a change of prophylactic antibiotic therapy from cloxacillin/cefotaxime to trimethoprim/sulfamethoxazole (TMP-SMX) was conducted in 2016. The study included consecutive patients undergoing lower extremity revascularization due to acute or chronic lower extremity arterial disease. The antibiotic regime was changed in between the two sampling periods (2014 -2016 versus 2016 -2017). The diagnosis of SSI was based on clinical examination and microbiological results, and severity was classified according to the Szilagyi classification. One hundred and twenty-two patients in the cloxacillin/cefotaxime and 67 patients in the TMP-SMX group were included. The SSI rates were 32.0% and 40.3%, respectively (p=0.25). The proportion of women were higher in the TMP-SMX group (32.8% versus 47.8%, respectively, p=0.043). No other differences between the two groups were found regarding patient, vascular surgery procedure characteristics or severity of SSI. Groin infection rate was higher in the TMP-SMX group (15.4% versus 30.5%, respectively, p=0.022). When adjusting for gender, groin infection was more common in the TMP-SMX group (Odds Ratio 2.5, 95% CI 1.1 -5.4). The groin SSI rate was higher after elective surgery in the TMP-SMX group (13.0% versus 27.8%, respectively, p=0.027), and also after adjusting for gender (Odds Ratio 2.6, 95% CI 1.1 -6.2). The change in antibiotic prophylaxis from Cloxacillin/Cefotaxime to TMP-SMX was associated with an increased rate of inguinal SSI in patients undergoing lower extremity revascularization, despite a possible Hawthorne effect.