Impact of an antimicrobial stewardship initiative to evaluate β-lactam allergy in patients ordered aztreonam

Purpose. An evaluation of the clinical and economic impact of an antimicrobial stewardship quality initiative (ASQI) focusing on allergy assessment in patients with a documented beta-lactam allergy prescribed aztreonam was conducted. Methods. This retrospective study was executed at a hospital with an interdisciplinary antimicrobial stewardship program (ASP). A total of 186 patients with self-reported beta-lactam allergies who were prescribed aztreonam while admitted during a 36-month time period surrounding the ASQI implementation were included. The primary study outcome was median time in hours to aztreonam discontinuation among nonanaphylactic patients. Results. After implementation of the ASQI, the percentage of patients continued on aztreonam for the duration of therapy was nearly cut in half, and a greater percentage of patients were switched to beta-lactam antibiotics. No adverse effects associated with beta-lactam therapy were observed in any study patient. Antimicrobial cost savings was not associated with any difference in clinical outcomes. Overall, hospitalwide aztreonam prescribing and aztreonam use declined. Institutional aztreonam orders per 1000 patient-days decreased from 1.5 to 1 after implementation of the ASQI. Additionally, hospitalwide aztreonam days of therapy per 1000 patient-days was reduced from 3.6 in the pre-ASQI period to 1.8 in the post-ASQI period. Conclusion. An ASQI that included critical evaluation of patient-reported beta-lactam allergies led to decreased aztreonam use, reduced antimicrobial expenditure, and similar clinical outcomes to those observed before implementation.