Why beta-lactam allergy mislabelling is dangerous

2 minute read


A new study reinforces determining whether someone is truly allergic to beta-lactams could have important long-term implications.


Most penicillin allergies aren’t real, but treating them as if they are helps fuel antibiotic resistance.

One in 10 people report they are allergic to beta-lactam antibiotics like penicillin, but the true prevalence of such allergies is much lower.

Consequently, patients who are not legitimately allergic to these medications have an increased risk of receiving inferior therapies and experiencing adverse outcomes in the short-term. Less is known about the long-term outcomes of patients with beta-lactam allergies.

Now, new US research published in JAMA Network Open, reports documented beta-lactam allergies were associated with an 18-44% increase in antibiotic resistant infections over an 11-year follow-up.  

“Health systems should prioritise initiatives to maximise the use of first-line antimicrobials and reduce unnecessary beta-lactam avoidance,” the researchers concluded.

Researchers examined the medical records of 20,000 patients diagnosed with sepsis, pneumonia or a urinary tract infection, 21% of whom had a documented beta-lactam allergy.

There was no association between beta-lactam allergy and mortality (the primary outcome) after accounting for factors such as age, sex, race, baseline kidney function, existing comorbidities and whether the patient was admitted to the intensive care unit.

However, there was an association with the secondary outcomes of methicillin-resistant Staphylococcus aureus (MRSA; 44% more likely compared to patients without a beta-lactam allergy) and vancomycin-resistant Enterococcus (VRE; 18% more likely) infection after controlling for the same confounding factors.

There was no association between beta-lactam resistance and Clostridium difficile infection and acute kidney injury.

The researchers encouraged healthcare systems to “support accurate allergy labelling and reduce the risk of unnecessary beta-lactam avoidance to improve patient outcomes”.

Penicillin allergy assessment and challenges have been shown to be feasible in general practice.

JAMA Network Open 2024, online 17 May

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