Implementation of an antimicrobial stewardship programme and reduction in carbapenemase-producing Enterobacterales in an Australian local health district.

Background: Carbapenemase-producing Enterobacterales (CPE) are increasingly seen in Australian hospitals. Antimicrobial stewardship (AMS) interventions have been shown to reduce rates of carbapenem-resistant organisms; data on their effect on CPE rates are limited.

Objectives: To explore the effect of a multi-site computer-supported AMS programme on the rates of CPE in an Australian local health district.

Methods: All laboratory CPE isolates between 2008 and 2018 were identified. Microbiological and demographic data, CPE risk factors and outcomes were collected. Monthly carbapenem use was expressed as DDD per 1000 occupied bed days (OBD). Hand hygiene compliance rates among healthcare workers were analysed. A computer-supported AMS programme was implemented district-wide in 2012. Bivariate relationships were examined using Pearson's and predictors of CPE isolates using time series linear regression.

Results: We identified 120 isolates from 110 patients. Numbers of CPE isolates and carbapenem use both showed a strong downward trend during the study period; the decreases were strongly correlated (0.80, 0.006). The positive relationship between carbapenem use and CPE isolation was maintained while adjusting for time (0.05, 0.001). Average yearly consumption of carbapenems fell by 20%, from 18.4 to 14.7 DDD/1000 OBD following implementation of the AMS programme. Hand hygiene compliance rates remained high throughout.

Conclusions: We demonstrated a reduction of CPE isolates in conjunction with reduced carbapenem use, longitudinally consolidated by a formal AMS programme. Prospective studies are needed to validate the effect of AMS on carbapenem resistance, especially in high-prevalence settings.