Hidden Risk of Penicillin Allergy Might Surprise You

August 27, 2018

Written by Vivian Lei

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Patients with a penicillin allergy were 69% more likely to develop MRSA infection and 26% more likely to contract C. difficile.                                                       

Why does this matter?
Physicians frequently encounter patients with a reported penicillin allergy. However, formal allergy testing of patients with documented penicillin allergies reveals that 95% are actually penicillin tolerant. Patients with a documented penicillin allergy are more likely to receive prescriptions for unnecessarily broad spectrum antibiotics which may lead to the development of drug resistant bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and healthcare associated infections such as Clostridium difficile.

Your penicillin allergy might be more dangerous than you thought
Investigators performed a matched cohort study analyzing data from patients enrolled in The Health Improvement Network, a database of outpatient primary care medical records from 11.1 million patients in the U.K. Adult patients with a newly documented penicillin allergy between 1995 and 2015 were matched with a comparison group of similar patients without a penicillin allergy. After adjusting for known risk factors for MRSA and C. diff infections, patients with penicillin allergies had a 69% increased risk of developing MRSA and a 26% increased risk for developing C. difficile. Once documented, a penicillin allergy resulted in increased use of β lactam alternative antibiotics, with a fourfold increased use of of macrolides and clindamycin and a twofold increased use of fluoroquinolones. Since less than 0.1% of patients with a listed penicillin allergy undergo confirmatory testing.  One way we can help is to refer for outpatient allergy testing, which may be an important and cost-effective method to reduce the incidence of MRSA and C. difficile.  Also, ask about the reported penicillin allergy.  Was it an actual allergy or might they be incorrectly labeled as allergic?

Source
Risk of meticillin resistant Staphylococcus aureus and Clostridium difficile in patients with a documented penicillin allergy: population based matched cohort study.  BMJ. 2018 Jun 27;361:k2400. doi: 10.1136/bmj.k2400.
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Reviewed by Thomas Davis