Prophylactic antibiotics given within 24 hours of surgery, compared with antibiotics given for 72 hours perioperatively, increased the rate of methicillin-resistant Staphylococcus aureus isolated from surgical site infections.

The purpose of this research was to find which method better prevented MRSA isolation from postoperative infection sites: the administration of postoperative infection control agents within 72 h of surgery, including the day of surgery, or the administration of these agents within 24 h of surgery. More than 3000 patients who underwent elective surgery of the digestive system were studied. Cefazolin or cefotiam was used as the prophylactic antibiotic. The number of patients, sex, age, clinical stage, incidence of surgical site infection (SSI), isolated bacteria, distal pancreatectomy with or without gastrectomy, the rate of laparoscopic surgery, and the rate of abdominoperineal resection (APR) were examined in a prospective controlled study over three time periods. There were no significant differences in the demographics of patients in the three periods. The duration of antibiotic administration was 96.1 +/- 11.2 h in period A, 18.2 +/- 2.7 h in period B, and 66.9 +/- 11.1 hours in period C (P < 0.05). There was no significant difference in the incidence of SSI in the three periods. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from the infectious site in 0.47% of patients in period A, and from 2.1% and 0.34% of patients in periods B and C, respectively, and the incidence of MRSA was significantly higher in period B as compared with periods A and C (P < 0.01). The isolation rates of MRSA and methicillin-sensitive S. aureus (MSSA) were both significantly higher in period B patients (P < 0.005). We concluded that the administration of prophylactic antibiotics within 24 h of surgery increased the rate of isolation of MRSA.