Prolonged antibiotic prophylaxis after cardiovascular surgery and its effect on surgical site infections and antimicrobial resistance

Background-Despite evidence supporting short antibiotic prophylaxis (ABP), it is still common practice to continue ABP for more than 48 hours after co ronary artery bypass graft (CABG) surgery. Methods and Results-To compare the effect of short (<48 hours) versus prolo nged (>48 hours) ABP on surgical site infections (SSIs) and acquired antimi crobial resistance, we conducted an observational 4-year cohort study at a tertiary-care center. An experienced infection control nurse performed pros pective surveillance of 2641 patients undergoing CABG surgery. The main exp osure was the duration of ABP, and main outcomes were the adjusted rate of SSI and the isolation of cephalosporin-resistant enterobacteriaceae and van comycin-resistant enterococci (acquired antibiotic resistance). Adjustment for confounding was performed by multivariable modeling. A total of 231 SSI s (8.7%) occurred after a median of 16 days, including 93 chest-wound infec tions (3.5%) and 13 deep-organ-space infections (0.5%). After 1502 procedur es using short ABP, 131 SSIs were recorded, compared with 100 SSIs after 11 39 operations with prolonged ABP (crude OR, 1.0; CI, 0.8 to 1.3). After adj ustment for possible confounding, prolonged ABP was not associated with a d ecreased risk of SSI (adjusted OR, 1.2; CI, 0.8 to 1.6) and was correlated with an increased risk of acquired antibiotic resistance (adjusted OR, 1.6; CI, 1.1 to 2.6). Conclusions-Our findings confirm that continuing ABP beyond 48 hours after CABG surgery is still widespread; however, this practice is ineffective in reducing SSI, increases antimicrobial resistance, and should therefore be a voided.