“Are you allergic to anything?” It’s a question asked in many settings, and perhaps most importantly in medicine.
Any number of allergies might be relevant to healthcare, sometimes in unexpected ways – for example some creams to treat skin complaints contain peanut oil that could cause an allergic response for a person with an allergy.
There are several tests that are used to determine if somebody is allergic to a substance such as a food or medication.
Allergy testing may include a specific IgE blood test to look for antibodies in the bloodstream linked to an allergic response.
Skin prick testing may also be used and involves scratching the surface of the skin and applying allergens in small amounts and monitoring any reaction.
An oral challenge test might also be needed to confirm an allergy. Possible trigger foods are consumed, usually in very small amounts that can then be increased if necessary to determine sensitivity.
Pathology’s role may be increasing though as research continues into improving allergy testing.
Earlier this year, researchers in Japan made a breakthrough towards creating a urine test for peanut allergy. Tests conducted in mice that were allergic to egg and milk showed that the compound prostaglandin D2 metabolite (PGDM) was present in high levels in the urine of allergic mice, and a higher level of PGDM correlated to a more severe allergy.
The researchers also tested urine samples from humans comparing the urine of patients with and without allergies.
High levels of PGDM were only found in people with food allergies, not in people with other allergic conditions such as asthma, allergic rhinitis (hay fever), and atopic dermatitis, or in participants without allergies.
Although this research is in its early stages, scientists in the field are gaining a better understanding of allergies and how pathology techniques can be used to make testing less invasive and more specific for patients.
Another area where the role of pathology may soon increase is testing for antibiotic allergies. A study of 400 children in Perth who had an antibiotic allergy listed on their medical records found that only 2% had an immediate severe reaction, and an astonishing 90% were not allergic.
Research efforts in Melbourne have seen similar findings in adults. A study of patients at Austin Health and Peter Mac who were labelled with antibiotic allergies found that 83% had been incorrectly classified.
Almost half (48%) of these patients were immunocompromised, and many were undergoing treatment for cancer or post-transplant care, meaning they were particularly vulnerable and could benefit greatly from having more antibiotic treatment options available to them.
Dr Jason Trubiano who conducted the research is Austin Health’s Director of Antimicrobial Stewardship and Drug and Antibiotic Allergy Services, and an Infectious Diseases Specialist at Peter MacCallum Cancer Centre. He is collaborating with the team from the National Centre for Infections in Cancer (NCIC), based at Peter Mac, to develop novel blood tests and testing programs so that vulnerable patients suspected of having severe allergies can be safely tested.
At present, antibiotic allergies may not be confirmed by testing when they are entered on a patient’s medical records, often in childhood. A label may result from symptoms such as a rash in childhood, that could have had a viral cause and was incorrectly linked to antibiotic treatment.
It may also be that some patients lose sensitivity over time and years later they have effectively grown out of their antibiotic allergy. Evolution in the approach to allergy testing could not only improve testing experiences and treatment for patients, but could also help tackle antibiotic resistance by ensuring appropriate prescribing.
Dr Stephen Adelstein is an immunopathologist with an interest in allergies, he said, “Allergies are an area where advancing our knowledge and improving the process of testing can greatly benefit patients. Testing methods that can reduce the need for oral challenges and skin prick tests have the potential to avoid allergic reactions that may be at best uncomfortable, and at worst life-threatening. It’s an exciting area for improving the lives of many people into the future.”