Penicillin Allergy Skin Testing as an Antibiotic Stewardship Intervention in Hematopoietic Cell Transplant Recipients

BACKGROUND: Penicillin allergy de-labeling can be an effective stewardship tool at reducing cost and the use of alternative non-β-lactam antibiotics. This study aimed to determine the effect of a pre-transplant penicillin allergy skin testing (PAST) protocol on antibiotic usage and costs in an immunocompromised hematopoietic cell transplant (HCT) population. METHODS: We conducted a retrospective study of adult HCT patients at the Cleveland Clinic from July 2010-September 2016. Routine AST for HCT patients reporting allergy to β-lactam antibiotics was implemented at our institution in July 2015. We compared days of antibiotic therapy (DOT) and antibiotic costs (AC) before and after the implementation of the AST protocol. Antibiotic usage for empiric treatment of suspected bacterial infection was captured as average DOT per 1000 patient days during the index hospitalization and AC were measured as dollars per 1000 patient days. Utilization of alternative antibiotics was compared with our standard formulary agent (piperacillin/tazobactam). RESULTS: Among the 1108 HSCT during the study period (N = 871 pre-and N = 237 post-PAST) β-lactam allergy was reported by 178 patients (141 [16%] pre- and 37 [16%] post-PAST, P = 0.83). PAST was performed on 8% (11/141) and 76% (28/37) of patients pre- and post-implementation. Only 2 positive PAST were noted (one in each group). There were no adverse reactions to PAST. There was no significant difference in the disease and transplant characteristics between the two groups. Average DOT (760 vs. 588; P = 0.03) and AC ($23,559 vs. $14,179; P = 0.012) decreased for all alternative antibiotics except levofloxacin (see Figures 1 and 2). Usage and cost of our institutional empiric formulary agent increased after AST implementation. CONCLUSION: The use of PAST to adjudicate reported β-lactam allergy in patients undergoing HCT is an effective antimicrobial stewardship strategy to lower usage and cost of alternative antibiotics and can facilitate prescribing of effective standard formulary agents when treating immunocompromised HCT patients at high-risk for infection. The impact of penicillin allergy de-labeling on Clostridium difficile infection and antibiotic resistance merits evaluation in future studies. DISCLOSURES: All authors: No reported disclosures.