Incidence of carbapenem-associated allergic-type reactions among patients with versus patients without a reported penicillin allergy.

This retrospective analysis sought to determine the comparative incidence of cross-reactivity associated with carbapenem antibiotic treatment among patients with versus those without penicillin allergy. We sought to determine whether the incidence of cross-reactivity is different between imipenem-cilastatin and meropenem. A total of 211 patients were treated with a carbapenem antibiotic. Included were 100 patients with and 111 patients without a documented or reported penicillin allergy. Within each group, subgroups of penicillin-allergic and penicillin-nonallergic patients were balanced equally between imipenem-cilastatin and meropenem. The incidence of patients with a reported or documented penicillin allergy experiencing an allergic-type reaction to a carbapenem was 11%, which is 5.2 times greater than the risk in patients who were reportedly not allergic to penicillin (P=.024). No difference in the occurrence of allergic-type reactions was observed between the 2 carbapenems.