Beta-Lactam Allergy? Let’s Try a Beta-Lactam Challenge!

September 18, 2024

Written by Amanda Mathews

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This retrospective study suggests that full dose antibiotic challenges for patients with listed beta-lactam antibiotic allergies can be safely accomplished in the ED.

“My mom said I was allergic to penicillin as a kid”
This was a retrospective chart review of patients who had a documented moderate, severe, or unknown beta-lactam allergy who then received a full dose of beta-lactam antibiotic in the study ED. Moderate reactions were hives, urticaria or swelling (not of the head or neck); severe reactions were anaphylaxis, swelling of the mouth/lips/tongue/throat, or difficulty breathing. Unknown reactions were not listed, or the patient did not know.  850 patients were screened, and 184 patients were included in the study. All the patients were to be admitted to the hospital. Most were being treated for pneumonia or urinary tract infection. Ceftriaxone was the most used antibiotic for the challenge in the study (83.2%).

After admission, 86.4% of patients had a beta-lactam antibiotic continued and 73.4% of patients had an update in their electronic medical record noting their antibiotic tolerance. Only 2.7% (5/184) patients developed an allergic reaction after full dose beta-lactam administration. All reactions were limited to mild reactions of rash or itching; there were no documented anaphylactic reactions. One patient had a reaction in the ED, and four had reactions after admission.

How will this change my practice?
While this study is limited due to its retrospective nature, single site, and exclusion of patients being discharged, it still is very exciting to me. Beta-lactam antibiotics are great choices for many common infections we treat in the ED (UTI, pneumonia, SSTI), and having an allergy listed to this class of antibiotics limits our choices for treatment. Almost ¾ of patients in this study had their allergy updated in the chart, which will only help their care moving forward. I would still have (and document) a careful shared decision-making conversation with a patient before treating them with any medication that has a documented allergy, no matter how mild it seems. But I will feel more comfortable encouraging patients to try a beta-lactam antibiotic challenge in the ED, if they are being admitted, knowing that the likelihood of severe reaction is very low.

Editor’s note: We covered a paper with a handy beta-lactam cross-reactivity chart. Reaction to a beta-lactam agent has more to do with the side chain than the beta-lactam ring structure. Given this, it’s not surprising there was very low rate of reaction to largely ceftriaxone administration (83.2%) among patients with predominately penicillin allergy (89.7%) listed. ~Clay Smith

Source
Full-dose challenge of moderate, severe, and unknown beta-lactam allergies in the emergency department. Acad Emerg Med. 2024 Aug;31(8):777-781. doi: 10.1111/acem.14893. Epub 2024 Mar 21. PMID: 38511401.