Ertapenem Safety in Patients with Penicillin Allergy

Cross-reactivity Between Penicillins and Carbapenems

• Carbapenems have molecular structures sufficiently dissimilar from penicillins, resulting in a very low risk of cross-allergy 1
• The meta-analysis demonstrated that carbapenems can be administered without prior testing in both severe and non-severe immediate-type penicillin allergies 2
• The risk of cross-reactivity between penicillins and any carbapenem is only 0.87% (95% CI: 0.32%-2.32%) 4

Clinical Recommendations for Ertapenem Use in Penicillin-Allergic Patients

• Ertapenem can be administered without prior allergy testing, regardless of the severity of the previous reaction, time elapsed since the index reaction, or whether the allergy is confirmed or suspected 1, 5
• Patients with non-severe, delayed-type penicillin allergy can receive any carbapenem, including ertapenem, without prior allergy testing 6, 7

Practical Approach

• For patients with penicillin allergy requiring ertapenem, document the nature of the previous reaction and proceed with ertapenem administration without prior testing 1, 7
• Monitor for potential hypersensitivity reactions, and consider administering the first dose in a monitored setting if there are specific concerns about a severe previous reaction 4