Abstract
BACKGROUND: Participants were patients with invasive breast cancer undergoing primary surgery. The aim was to test whether a single dose of amoxicillin-clavulanic acid would reduce wound infection at 30 days postoperatively, and to identify risk factors for infection. METHODS: Participants were randomised to either a single bolus of 1.2 g intravenous amoxicillin-clavulanic acid after the induction of anaesthesia (intervention) or no antibiotic (control). The primary outcome was the incidence of wound infection at 30 days postoperatively. RESULTS: There were 871 evaluable patients. Of these, 438 received prophylactic antibiotic and 433 served as controls. Seventy-one (16.2 per cent) patients in the intervention group developed a wound infection by 30 days, while there were 83 (19.2 per cent) infections in the control group. This was not statistically significant (odds ratio (OR) 0.82, 95 per cent c.i. 0.58 to 1.15; P = 0.250). The risk of infection increased for every 5 kg/m2 of BMI (OR 1.29, 95 per cent c.i. 1.10 to 1.52; P = 0.003). Patients who were preoperative carriers of Staphylococcus aureus had an increased risk of postoperative wound infection; however, there was no benefit of preoperative antibiotics for patients with either a high BMI or who were carriers of S. aureus. CONCLUSION: There was no statistically significant or clinically meaningful reduction in wound infection at 30 days following breast cancer surgery in patients who received a single dose of amoxicillin-clavulanic acid preoperatively. REGISTRATION NUMBER: N0399145605 (National Research Register).