Penicillin allergy skin testing as an antibiotic stewardship intervention reduces alternative antibiotic exposures in hematopoietic stem cell transplant recipients.

BACKGROUND: Antibiotic allergy de-labeling using penicillin allergy skin testing (PAST) can reduce the use and cost of alternative, non-β-lactam antibiotics in general inpatient populations. This strategy's role in hematopoietic stem cell transplant (HSCT) recipients is unclear.

METHODS: This study aimed to determine the effect of a pre-transplant PAST protocol on antibiotic use, days of therapy (DOT), and cost in an immunocompromised population at a single center from 7/1/2010-2/1/2019. Patients who received chimeric antigen receptor (CAR) T-cell therapy and those who underwent transplantation in the outpatient setting were excluded.

RESULTS: Of 1560 patients who underwent inpatient HSCT during the study period, 208 reported β-lactam allergy (136/844 [16%] pre- and 72/716 [10%] post-implementation; P < .001). PAST was performed on 7% and 54% of HSCT recipients pre- and post-implementation, respectively. Only two positive PAST were noted. There were no adverse reactions to PAST. There were no significant differences in the disease and transplant characteristics between the two groups. Days of therapy and cost of alternative antibiotics significantly decreased post-implementation (mean 788 vs 627 days, P = .01; mean $24 425 vs $17 518, P = .009).

CONCLUSION: Penicillin allergy skin testing adjudicates reported β-lactam allergy in HSCT recipients, lowering use, DOT, and cost of alternative antibiotics and promoting effective formulary agents to treat immunocompromised HSCT recipients.