Clinical importance of carbapenem hypersensitivity in patients with self-reported and documented penicillin allergy.

The risk of carbapenem hypersensitivity in patients with self-reported or documented penicillin allergy needs to be determined so that practitioners can make better-informed decisions regarding antibiotic therapy for this patient population. The risk of cross-reactivity between penicillin and carbapenem antibiotics initially was reported to approach 50%. Recent retrospective studies have suggested that the clinical risk of cross-hypersensitivity between these two drug classes is 9.2-11%, which is significantly lower than initially reported. Patients whose history of penicillin allergy is self-reported and is not type 1 may be at moderate risk for hypersensitivity when treated with a carbapenem antibiotic. The risk of hypersensitivity appears to be higher in patients whose penicillin allergy was documented by a health care provider, those with several antibiotic allergies, and those with a positive penicillin skin test result or a history of type 1 penicillin hypersensitivity.