Association of antibiotic utilization measures and reduced incidence of infections with extended-spectrum beta-lactamase-producing organisms.

With the overuse of expanded-spectrum cephalosporins, especially ceftazidime, outbreaks of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli infections have been reported. In this prospective observational study, we demonstrated that the addition of piperacillin/tazobactam to the formulary and the restriction of ceftazidime were associated with a decrease in the percentage of ceftazidime-resistant isolates. When the use of ceftazidime decreased by 96.43%, and the use of piperacillin/tazobactam increased by over 50% during the 9-month study period, a concomitant decrease was found in the percentage of colonization and infection by ESBL-producing E. coli or K. pneumoniae in patients admitted to the intensive care unit. Results from this 9-month intervention study support the concept that levels of local and institutional use of ceftazidime are of substantial importance to the emergence and persistence of endemic ceftazidime-resistant K. pneumoniae.