Hospital-based testing safely removes incorrect allergy labels
Researchers from Melbourne have led what is described as the world's largest study examining penicillin allergy, with findings suggesting that most patients labelled as allergic to penicillin are not truly allergic. Published in Clinical Infectious Diseases, the study provides evidence that penicillin allergy testing can be safely incorporated into routine hospital practice at scale, potentially improving antibiotic prescribing and patient outcomes.
Penicillin allergy labels are common in clinical settings, with around one in 10 hospitalised patients recorded as having a penicillin allergy. However, these labels can significantly limit treatment options, often resulting in the use of broader-spectrum or less effective antibiotics
The international study involved more than 5,000 patients across 40 hospitals in Australia, New Zealand, the United Kingdom, the United States, Canada, Malaysia, South Africa, and Hong Kong. The research was led by Austin Health in collaboration with the University of Melbourne, the Peter Doherty Institute for Infection and Immunity and the National Allergy Center of Excellence (NACE) at the Murdoch Children's Research Institute.
As part of the study, 1,573 patients received a supervised test dose of penicillin. Researchers found that 95% of these patients could be safely confirmed as not being allergic to penicillin. Following assessment, their medical records were updated, allowing clinicians to prescribe first-line antibiotic therapies that may previously have been avoided because of an allergy label.
The findings are significant because inaccurate penicillin allergy labels can affect both individual patient care and broader antimicrobial stewardship efforts. Patients incorrectly labelled as allergic may receive alternative antibiotics that are less effective, more costly or associated with a greater risk of antimicrobial resistance. In addition, allergy labels have been linked to longer hospital stays, increased health care costs and higher rates of readmission.
"Around 10% of hospitalised patients globally report a penicillin allergy; however, most are not truly allergic, often because they were misdiagnosed in childhood, outgrew it or it's been years since their last reaction," Professor Jason Trubiano, Head of Infectious Diseases at the University of Melbourne, Director of Infectious Diseases and Immunology at Austin Health and an infectious diseases physician, said.
"Misdiagnosis can result in inappropriate antibiotic prescribing, longer hospital stays, increased health care costs and more readmissions," Professor Trubiano said.
The study builds on earlier work demonstrating that penicillin allergy testing could be performed safely in smaller patient cohorts and specialist settings. The latest research extends those findings across multiple countries and health systems, providing evidence that testing can be delivered as part of routine care rather than being restricted to specialist allergy services.
"Our previous studies showed penicillin allergy testing could be done safely in smaller patient groups and specialist settings. This global study is a game-changer," Professor Trubiano said.
"For the first time, we have shown this approach can be safely implemented at scale across entire hospital systems, using technology to support clinicians and allowing hospitals worldwide to deliver this testing as part of routine care. For patients, that means faster access to the most effective antibiotics and better treatment outcomes," Professor Trubiano said.
A key component of the study was the evaluation of a purpose-built smartphone assessment tool designed to help clinicians identify patients at low risk of true penicillin allergy. The tool enabled doctors, pharmacists and nurses to determine suitability for a supervised test dose and facilitated allergy assessment in hospitals that did not have specialist allergy services available.
The researchers believe this approach could help overcome one of the major barriers to widespread allergy assessment by making testing more accessible and easier to integrate into existing clinical workflows. The model is intended to support safe risk stratification and expand the number of patients who can be assessed during routine hospital admissions.
"This study shows penicillin allergy testing can be safely integrated into everyday hospital care, ensuring patients receive the most appropriate and effective treatment. The model is already being rolled out in hospitals across Australia and internationally," University of Melbourne PhD candidate and Austin Health Drug Allergy Pharmacist Elise Mitri said.
The research team is now extending the model into paediatric settings. In partnership with NACE, the program will be expanded to six Australian hospitals to assess children with reported penicillin, cephalosporin or sulfonamide allergies.
About 5% of hospitalised children report a penicillin allergy, with prevalence increasing with age. Researchers hope that earlier assessment and clarification of allergy status will help ensure children receive the most appropriate antimicrobials when required and avoid carrying inaccurate allergy labels into adulthood.
"The new study will help assess hundreds of children with a reported penicillin, cephalosporin or sulfonamide allergy," Professor Kirsten Perrett, Director of NACE and Population Allergy Group Leader at the Murdoch Children's Research Institute, said.
For clinicians, the study provides further evidence that many reported penicillin allergies may benefit from formal assessment and de-labelling where appropriate. By demonstrating that supervised oral challenge testing can be delivered safely across diverse health care settings, the findings support broader implementation of penicillin allergy assessment as part of routine hospital care, with potential benefits for antimicrobial stewardship, clinical outcomes and health system efficiency.