© DR P. MARAZZI/SPL
September 2023
Assessing penicillin allergy: single oral penicillin dose effective
By Rebecca Jenkins
A single oral penicillin dose is a safe and effective alternative to skin testing when challenging patients with a low-risk history of penicillin allergy, a study finds.
Fewer than 5% of patients labelled with a penicillin allergy are truly allergic, researchers wrote in JAMA Internal Medicine, but currently two-stage skin testing followed by oral challenge is needed to remove the penicillin allergy label in adults.
In the Penicillin Allergy Clinical Decision Rule (PALACE) trial, 382 adults from six specialised centres, including three in Australia, were randomised to direct oral penicillin challenge or standard care of two-step skin testing followed by oral challenge.
All participants were deemed at low risk for a reaction to penicillin following assessment with the validated PEN-FAST tool (PEN-FAST score less than 3).
Researchers found an immune-mediated reaction occurred in 0.5% of both the direct oral challenge and the standard care groups, with an upper one-sided confidence interval below the noninferiority margin of five percentage points.
There was also no difference between the groups in immediate or delayed adverse events reported by day five of the oral penicillin challenge, the researchers reported.
‘Compared with skin testing, a direct oral penicillin challenge is less resource- and time-intensive, is less expensive, and has the potential to be performed outside of the specialist allergy setting, providing a scalable approach to address low-risk, unverified penicillin allergy in diverse treatment settings internationally,’ the researchers wrote.
Study investigator Professor Jason Trubiano, Director of Infectious Diseases at Austin Health and Laboratory Head for Austin Health’s Centre for Antibiotic Allergy and Research, Melbourne, said there were currently insufficient services in Australia to provide traditional skin testing for penicillin allergy.
‘One in 10 patients report a penicillin allergy with increased risks of drug-resistant infections, poor infection outcomes and higher hospital costs,’ he told Medicine Today.
‘The study results mean that in an appropriately assessed patient, somebody considered to have a low-risk penicillin allergy, a simple oral test dose can be done safely to prove or disprove the allergy, under medical supervision.’
Professor Trubiano stressed that currently the evidence for this procedure was in stable patients in the hospital outpatient setting with low-risk penicillin allergies, such as childhood reactions.
‘Whilst there are data for the same procedure being done in patients in the hospital setting, the data are limited for patients who are critically ill or pregnant,’ he said.
However, Professor Trubiano said the field of drug and penicillin allergy was moving forward significantly in Australia and he anticipated results from trials led by the Centre for Antibiotic Allergy and Research examining direct oral challenge in the perioperative and ICU setting being released in the next 12 months.