postoperative wound infection in patients undergoing coronary artery bypass graft surgery: a prospective study with evaluation of risk factors

PURPOSE: Wound infection is an important cause of morbidity and occasional mortality after coronary artery bypass graft surgery (CABG). The aim of this study was to report postoperative wound infection in CABG surgery patients. METHODS: Consecutive patients undergoing CABG surgery between January 1998 and October 1999 have been studied. The exclusion criteria included, age less than 30 years, penicillin / cephalosporin allergy and associated other cardiac pathologies. The parameters studied were age, sex, obesity, hypertension, diabetes, myocardial infarction, chronic renal failure, previous surgeries, alcohol consumption, smoking, length of pre and postoperative hospital stay, antibiotic prophylaxis, MRSA screening, and duration of surgery. Wounds were classified as per modified CDC′s NNIS criteria. Suspected sites of infection were cultured and antibiotic susceptibility of cultured organisms was tested. Postoperative follow up was for two months. RESULTS: Six hundred and fifteen patients were studied. Of these 116 (18.86%) developed SSI, involving sternum 75%, leg 21.3%, and forearm sites 3.44%. Organisms isolated at sternum site were MSSE, MRSA, and MRSE, at leg site E. coli and MSSE, and at forearm site MSSE and MSSA. Sternal site, obesity, diabetes mellitus and female sex were associated with significantly higher infection rates (p= 0.001). No antibiotic protocol proved more effective. SSI increased the postoperative hospital stay and the total treatment cost. CONCLUSIONS: Post CABG surgery SSI rate is high. Sternum and leg are the common infection sites. Obesity, uncontrolled diabetes mellitus and female sex are associated with higher infection rates. "Higher" antibiotics do not lower postoperative infection rates.