Safe, sustained reduction in meropenem and piperacillin/tazobactam use in a medical high dependency unit

There is widespread overuse of ultra-broad spectrum antibiotics (UBSA) such as meropenem and piperacillin/tazobactam (PTZ). Reductions in their use are needed to preserve their effectiveness.

Using electronic prescribing data we recorded administrations of meropenem and PTZ per month in a 12-bed medical high dependency unit (HDU) from April 2016 to March 2019. During this time there were three interventions (an antimicrobial stewardship round began in March 2017, PTZ was removed from empirical prescribing guidelines in May 2017, and a restricted antimicrobial audit began in June 2017). The latter two interventions were prompted by a national PTZ shortage.

In 2016/17 meropenem and PTZ use was 56 and 113 daily defined doses/100 acute occupied bed days (AOBD) respectively, falling to 32 and 60 in 2017/18, and to 25 and 38 in 2018/19. This represented a 55% reduction in meropenem use and a 77% reduction in PTZ use over 2 years. The drop in use was due to both fewer patients being started on UBSA and shorter durations of treatment. The use of 4C antibiotics (clindamycin, cephalosporins, co-amoxiclav and ciprofloxacin/levofloxacin) did not increase. There was no increase in unit mortality, or change in the prevalence of ESBL-producing organisms.

We describe a multi-modal intervention that, coupled with strong clinical engagement, resulted in a safe, sustained reduction in both meropenem and PTZ use in a medical HDU, without using more 4C antibiotics. We hypothesize that “top down” policies helped reduce UBSA initiation, whereas a “bottom-up” ward-based initiative helped review and stop unnecessary use.