Evidence Supporting the Use of Cephalosporin Antibiotics in Penicillin-Allergic Patients

Promoting β-lactam utilization through suppression of electronic medical record cross-allergy alerts

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PURPOSE

Current literature surrounding management of patients with reported β-lactam allergies focuses on allergy delabeling. Standard clinical decision support tools have not been optimized to be compatible with the currently accepted cross-reaction rate of 1% to 2%. This potentially promotes use of non-β-lactam antibiotics, which are often not first-line therapy and may carry increased risks. The impact of electronic medical record (EMR) clinical decision support tool optimization on utilization of β-lactam antibiotics in β-lactam-allergic patients was evaluated.

METHODS

A retrospective pre-post β-lactam cross-allergy EMR alert suppression quality improvement intervention cohort study of β-lactam-allergic adult inpatients prescribed antibiotics was conducted. Preintervention baseline data were collected for an initial cohort admitted during September 2018. The intervention, in which clinical decision support rules were updated to display β-lactam cross-sensitivity allergy alerts only for β-lactam-allergic patients with documentation of organization-defined high-severity reactions of anaphylaxis, hives, and shortness of breath, was implemented August 20, 2019. The postintervention cohort included patients admitted during September 2019.

RESULTS

A 91% increase in the percentage of β-lactam-allergic patients who received a β-lactam agent at any time during their admission was noted after the intervention (26.6% vs 51%, P < 0.001). Statistically significant decreases in prescribing of alternative antibiotic classes were seen for fluoroquinolones (decrease from 45.3% to 26%, P < 0.001), aminoglycosides (decrease from 9.4% to 2.9%, P = 0.002), and aztreonam (decrease from 30% to 16.7%, P < 0.001).

CONCLUSION

EMR β-lactam cross-allergy alert optimization consistent with current literature significantly improved the utilization of alternative β-lactam subclasses, mostly through β-lactam prescribing as initial therapy in β-lactam-allergic patients.

Cross-reactivity in β-Lactam Allergy

β-Lactam drugs (penicillins, amoxicillin, and cephalosporins) account for 42.6% of all severe drug-induced anaphylaxis. In this review, we focus on clinically significant immunologic cross-reactivity in patients with confirmed penicillin allergy to cephalosporins, and the structural involvement of the R₁ and R₂ chemical side chains of the cephalosporins causing IgE-mediated cross-reactivity with penicillin and other cephalosporins. Skin tests predict IgE-mediated reactions and showed cross-reactivity between penicillins and early generation cephalosporins that shared side chains, but confirmatory challenge data are lacking. Later-generation cephalosporins, which have distinct side chains, do not have any skin test cross-reactivity with penicillin/amoxicillin. There is debate as to the involvement of R₂ side chains as the antigenic determinants that cause IgE-mediated hypersensitivity with various cephalosporins. Avoidance of cephalosporins, when they are the drug of choice in a penicillin-allergic individual, results in significant morbidity that outweighs the low risk of anaphylaxis. We conclude that there is ample evidence to allow the safe use of cephalosporins in patients with isolated confirmed penicillin or amoxicillin allergy.