Long-term effects of an antimicrobial stewardship programme at a tertiary-care teaching hospital

Antimicrobial stewardship has been shown to reduce unnecessary antibiotic use, but there are few data on the long-term benefits of such a programme. Antimicrobial use over a 13-year period since implementing an antimicrobial stewardship programme (ASP) at our institution was examined. Nosocomial rates of Clostridium difficile infection (CDI) and antimicrobial susceptibility patterns of common nosocomial micro-organisms over the same period were also reviewed. Total antimicrobial use decreased by 62.8% (P<0.0001). There were decreases in use of aminoglycosides (-91.3%; P<0.0001), cephalosporins (-68.3%; P<0.0001), extended-spectrum penicillins (-77.7%; P<0.0001), macrolides (-27.2%; P=0.002), clindamycin (-95.9%; P<0.0001) and quinolones (-78.7%; P<0.0001). Antifungal use decreased by 71.0% (P<0.0001). There were increases in the use of carbapenems (+736%, P<0.0001) and anti-MRSA drugs (+73.3%; P<0.0001). There was a 56.7% (P=0.007) reduction in nosocomial MRSA infections. Nosocomial CDI rates decreased by 42.6% (P=0.005) between 2003 and 2010 and then increased to near baseline levels following implementation of more sensitive testing for detection of CDI in 2011. There were decreases in the rate (-71.9%; P=0.001) and percentage (-51.4%; P<0.0001) of quinolone-resistant Pseudomonas aeruginosa. There were decreases in the rate (P<0.0001) and percentage (P=0.02) of carbapenem-resistant P. aeruginosa following implementation of a policy restricting ciprofloxacin use. We have demonstrated sustained reductions in both antimicrobial use and drug-resistant organisms following implementation of an ASP.