As we hear about rises in iGAS, the issue of antibiotic allergy – and specifically penicillin allergy – labelling comes to the fore. A good review here outlines some of the issues in this complex space, and makes some helpful suggestions about how this could be improved.
So, what’s the issue with antibiotic allergy labelling? Somewhere between 10 and 25% of most populations that have been studied across the world are labelled as “penicillin allergic”. However, when you delve into that, only somewhere between 1 and 10% of those who carry the “penicillin allergic” label are actually allergic to penicillin in any meaningful sense. For reasons that are not very clear, most streptococci remain remarkably susceptible to penicllins. So, if we lose this drug family due to spurious penicillin allergy, we are reaching up the shelf when we don’t need to.
Why is spurious penicillin allergy so common then? Penicillin allergy labels are often added in childhood and can come from local skin reactions due to exposure to viruses and not penicillin, interactions between specific viruses and specific drugs, local reactions to penicillin that are not meaningful, non-allergic penicillin side effects, family history, and sometimes just made up (perhaps driven by fear)!
How do we tackle this issue? Penicillin allergy de-labelling is a crucial part of any antimicrobial stewardship strategy. There are two principle ways to go about penicillin de-labelling – one is using patient history alone (which is easy but more risky), the other is to do skin and/or ingestion testing (which is harder but less risky). There’s a bit of a tech gap here in that we are lacking an accurate, cheap, and rapid point-of-care test to establish whether an individual has a meaningful penicillin allergy. Whilst we wait for that, we need to work on a multidisciplinary penicillin allergy de-labelling strategy as part of our antimicrobial stewardship programmes.