ObjectiveTo evaluate the effect of antimicrobial stewardship program (ASP) on perioperative antimicrobial selection and incidence of postoperative infection in patients undergoing thoracic surgery.MethodsFrom 2015 to 2016, patients who underwent lung or esophageal surgery in the department of thoracic surgery of a hospital and without infection before operation were selected. Patients in 2015 were in control group (before intervention), and patients in 2016 were in trial group (after intervention). ASP was performed in 2016, clinical pharmacists and doctors in infectious department standardized antimicrobial use through conducting realtime intervention in doctors’ orders for the use of carbapenems and fluoroquinolones. Standardized antimicrobial use and occurrence of surgical site infection(SSI) before and after the implementation of ASP were compared.ResultsBefore and after intervention, 953 and 1 061 patients were enrolled respectively. Incidence of SSI in patients undergoing esophageal and lung surgery before and after intervention were 1.57% and 1.70% respectively, with no significant difference (χ2=0.047, P=0.829). The rate of recommended use of antimicrobial agents (cefuroxime or cefmetazole) for preventing SSI rose from 37.15% (354/953) before intervention to 69.75% (740/1 061) after intervention, with a statistically significant difference before and after intervention (χ2=215.025, P=0.000). Comparison in AUD of antimicrobial agents in thoracic surgery before and after intervention showed that AUD of ertapenem decreased by 52.46% (8.12 VS 3.86), cefuroxime and cefmetazole increased by 98.00%(7.49 VS 14.83) and 95.18%(4.98 VS 9.72) respectively; ceftriaxone decreased by 85.29% (12.03 VS 1.77).ConclusionThe implementation of ASP reduced the usage of ertapenem and ceftriaxone, standardized preventive medication in thoracic surgery, and didn’t cause changes in the incidence of SSI in lung and esophageal surgery.