Is it safe to use carbapenems in patients with a history of allergy to penicillin?

Objectives: The purpose of this retrospective study was to ascertain the clinical safety of administering carbapenems, namely imipenem/cilastatin and meropenem, in patients with a history of penicillin allergy compared with administering carbapenems in patients with no reported penicillin allergy. Carbapenems are similar in chemical structure to the penicillins and therefore are associated with a risk for allergic cross-hypersensitivity. Carbapenems are commonly avoided in patients with a reported penicillin allergy on the basis of a potential cross-hypersensitivity with penicillin, however, very few studies have been conducted describing the incidence of cross-hypersensitivity between penicillin and carbapenems. Methods: A retrospective review was conducted in a total of 266 patients who were administered either imipenem/cilastatin or meropenem. The patients were admitted to the Cleveland Clinic Health System-Eastern Region Hospitals during the years 2001 and 2002. Results: Fifteen of the 163 patients (9.2%) with reported penicillin allergy developed a hypersensitivity reaction to meropenem or imipenem/cilastatin whereas 3.9% of the 103 patients without penicillin allergy developed a hypersensitivity reaction to meropenem or imipenem/cilastatin. These results are not statistically significant. Conclusions: Based on this study and other similar studies, the true incidence of cross-hypersensitivity reactions between penicillin and carbapenems may be lower than previously reported. Carbapenem use may be reasonable for penicillin allergic patients if caution is exercised.