Protective effect of intraoperative re-dose of prophylactic antibiotics on surgical site infection in diabetic patients: a retrospective cohort study.

Background: Surgical site infection (SSI) has a high incidence in diabetic surgical patients. Preoperative antibiotic prophylaxis followed by an intraoperative re-dose was a common strategy in diabetic prolonged procedures. However, there were lacking studies on the relative benefits of this strategy on SSI. Our study aimed to clarify the effect of intraoperative re-dose of prophylactic antibiotics on SSI in diabetic patients. Methods: A total of 1,840 diabetic patients with prolonged surgeries were included and Cefazolin was the only type of antibiotic prophylaxis. We assessed the relationship between intraoperative re-dose of cefazolin and 30-day incidence of SSI using a retrospective cohort study method. Results: There were 361 diabetic cases with preoperative antibiotics only and 1,479 cases with pre- plus intraoperative antibiotics, in which 60 subjects suffered from SSI. Pre- plus intraoperative prophylaxis group had a lower rate of SSI in the overall and subgroup analyses when compared with preoperative only group. Operation location, combined with hypertension, poor blood glucose control, high WBC count and ASA score >2 were significantly associated with an increased risk of SSI for diabetic surgical patients (all P<0.05). Intraoperative re-dose of prophylactic antibiotics was statistically related to a lower incidence rate of SSI than preoperative prophylaxis alone (crude RR = 0.47; 95% CI, 0.27-0.82; P<0.01), while the association remained significant even after adjusting the potential confounders (adjusted RR = 0.51; 95% CI, 0.29-0.90; P=0.02). Conclusions: For diabetic patients, intraoperative re-dose of prophylactic antibiotics may be an independent protective factor for the prevention of SSI. A specific perioperative antibiotics injection strategy should be encouraged for diabetic patients with prolonged surgeries to minimize the possibility of SSI.