Antibiotic Prescribing for Cellulitis in the Absence of Penicillin-Cephalosporin Cross-Reactivity Alerts: A Retrospective Study.

Cephalosporins are often avoided in patients with penicillin adverse drug reaction (ADR) labels. In our institution's electronic medication management system, penicillin and cephalosporin ADR labels do not generate cross-reactivity alerts. Penicillins and cephalosporins are preferred treatments for cellulitis. We aimed to describe penicillin, cephalosporin, and non-penicillin, non-cephalosporin (NPNC) prescribing for inpatients with cellulitis in the presence/absence of penicillin and/or cephalosporin ADR labels. Index cellulitis admissions were included from 2017 to 2024 where at least one penicillin, cephalosporin, or NPNC was administered, and were categorized according to the presence/absence of penicillin and/or cephalosporin ADR labels. Penicillin, cephalosporin, and NPNC prescribing was compared between groups with and without labels using odds ratios (OR) with 95% confidence intervals (CI). Of the 8374 included index admissions, 7567 had no penicillin/cephalosporin labels, 729 had penicillin-only labels, 42 had cephalosporin-only labels, and 36 had both labels. Inpatients with penicillin labels were significantly more likely (OR 13.07; 95% CI, 11.05-15.45) to be prescribed cephalosporins than those without labels. There were no differences in penicillin prescribing between those with cephalosporin labels and those without labels (OR 1.04; 95% CI, 0.44-2.47). Inpatients with penicillin and/or cephalosporin labels were 6 to 52 times more likely to receive NPNC antibiotics than those without labels. The absence of cross-reactivity alerts was associated with increased cephalosporin use for cellulitis in inpatients with penicillin ADR labels, sparing NPNC antibiotics that may be less effective. The removal of cross-reactivity alerts may be effective for increasing cephalosporin prescribing for inpatients with penicillin ADR labels.