Researchers Reveal Link Between Penicillin Allergy Label and Severe Infections

in Drug Allergy
Published: March 14, 2018

Photo: Getty
Patients avoiding penicillin because of a suspected allergy to the antibiotic face a higher risk of developing either of two types of severe infections called Staphylococcus aureus (MRSA) and Clostridium difficile (C. difficile), according to a new study.

In these patients, “over a quarter to half of the risk of new infection was attributable to the alternative antibiotics,” Dr. Kimberly Blumenthal, study author and quality director of allergy and immunology at Massachusetts General Hospital, told MedPage Today.

Using a U.K. health database of adults the researchers located about 64,000 patients with a reported penicillin allergy. They compared their health data against a control group of just over 237,000 people with no such allergy. They followed the two groups, and did a six-year follow-up analysis.

In the group who relied on alternative antibiotics because of a previously diagnosed penicillin allergy, 1,345 patients developed methicillin-resistant Staphylococcus aureus (MRSA). As well, 1,688 of this group developed C. difficile infection.

The patients hadn’t done testing to confirm their allergy to penicillin. This means they might have been avoiding the antibiotic when they didn’t really need to.

What’s the Takeaway on Penicillin?

Past studies have found that over 90 of patients who report a penicillin allergy actually can tolerate this more effective and cheaper antibiotic. Allergists recommend retesting to see whether you’ve outgrown the allergy.

Dr. David Lang, chairman of the department of allergy and immunology at the Cleveland Clinic says Blumenthal’s finding about infections adds an important reason for physicians to refer penicillin-allergic patients to an allergist. “Nine out of 10 – or even 19 of 20 – times we will be able to reduce the patient’s risk for bad outcomes by removing this label,” Lang told Allergic Living.

Blumenthal’s study was presented at the AAAAI/WAO joint meeting in Orlando in March 2018.