Impact of carbapenem restriction on the antimicrobial susceptibility pattern of Pseudomonas aeruginosa isolates in the ICU

Background: Rates of carbapenem-resistant Pseudomonas aeruginosa are increasing. Aggressive prevention strategies, including instituting antimicrobial stewardship programmes, are essential for combating antimicrobial resistance. Objectives: We conducted this study to compare the antimicrobial susceptibility pattern of P. aeruginosa before and after carbapenem restriction. Methods: We conducted a two-phase retrospective study in an adult ICU. The first phase was from May until July 2016 (before carbapenemrestriction), whereas the second phasewas fromSeptember until November 2016 (while implementing carbapenem restriction). The antimicrobial susceptibility pattern of P. aeruginosa was reviewed in August and December 2016. The measure of carbapenem-resistant P. aeruginosa was the proportion of resistant isolates (percentage resistant). The measure of antibacterial consumption in the study phases was DDDs/1000 patient days. Results: The overall carbapenem consumption decreased significantly in the second phase, from 28.44 to 11.67 DDDs/1000 patient days (P = 0.012). The resistance of P. aeruginosa to imipenem and meropenem decreased significantly from 76.0% to 38.5% (P = 0.019) and from 74.1% to 30.0% (P = 0.012), respectively. Susceptibility of P. aeruginosa to other antibacterials was not affected by carbapenem restriction. Conclusions: These data suggest that restricting carbapenems, even for a short duration, may be an effective strategy for managing the problem of carbapenem resistance in P. aeruginosa.