Cross-reactivity of beta-lactam antibiotics.

BUMC PROCEEDINGS 2001;14:106–107 D uring a drug history, the most common drug allergies cited are those experienced after the administration of a penicillin, with a reported allergy incidence of 1% to 10% in patients who receive drugs in this class (1). Penicillins, as well as other beta-lactam antibiotics such as cephalosporins, carbapenems, and monobactams, contain a beta-lactam ring (2). The safety of administering beta-lactam antibiotics to penicillinallergic patients is highly debated and is based mainly on anecdotal information regarding the incidence of cross-reactivity. Another factor complicating safety is the validity of the reported allergy. For example, patients experiencing gastrointestinal upset with penicillin administration often mistakenly report this reaction as an allergy on subsequent interview. In addition, <20% of patients who report penicillin allergies have a positive result when given a penicillin skin test (3). However, Preston et al studied the accuracy of self-reported penicillin allergy at their institution (1). Patients enrolled in the study were determined to be allergic or intolerant through an interview conducted by a pharmacist. Of the 117 patients enrolled in the study who reported having a penicillin allergy, the majority (82.9%) were classified as having a true allergy, and 17.1% were classified as intolerant. The purpose of this paper is to discuss the available data concerning the safety of administering cephalosporins, carbapenems, and monobactams to penicillin-allergic patients.