Shifts in antimicrobial consumption and infection rates before and during a piperacillin/tazobactam shortage.

Objectives: Anti-infective shortages represent a growing threat to optimum management of infected patients and alter the institutional selective pressure against hospital-acquired infections (HAIs). The objective of this analysis was to assess the impact of a shortage of piperacillin/tazobactam (TZP) on overall antibacterial use and HAI rates at an academic institution.

Methods: Antimicrobial use and infection data were extracted from TheraDoc Clinical Surveillance Software (Premier, Inc.) for adult patients and were stratified as pre-shortage (October-December 2014) and post-shortage (February-April 2015). Paediatric and emergency department use were excluded. Antimicrobial use was reported as percent change and defined daily doses (DDD)/1000 patient-days (PD). Pre- and post-shortage vancomycin-resistant enterococci (VRE) and Clostridium difficile-associated diarrhoea (CDAD) rates were normalised to 1000 PD/month.

Results: Total use of target antimicrobials remained constant before and after TZP shortage (990.29 vs. 957.77). Total TZP use fell 95.2% (81.1 vs. 3.9). Total meropenem use rose 96.0% (42.3 vs. 82.9) after the shortage, driven by a 125.4% increase in use for non-ICU patients. Cefepime and ceftazidime use rose 97.9% (28.2 vs. 55.8) and 94.2% (1.6 vs 3.0), respectively. Cefepime use in non-ICU patients rose 223.2%. Fluoroquinolone consumption did not differ between periods. CDAD rates decreased (-21.8%), whilst VRE rates doubled during the shortage (0.6 vs. 1.3 infections/1000 PD/month).

Conclusions: Whilst overall antimicrobial use appeared steady, the TZP shortage resulted in increased use of multiple other antimicrobials. The doubling of VRE rates is concerning and illustrates the need for increased antimicrobial stewardship vigilance and education in response to shifting prescribing patterns during shortages.