A Study of the Impact of Penicillin Allergy on Antimicrobial Resistance and ouTcomes

Study hypothesis: Patients with a penicillin allergy record are more likely to have resistance to non-penicillin antibiotics in their normal flora and that this will increase their risk of treatment failure with non-penicillin antibiotics. In particular, penicillin allergic patients admitted with COVID-19 who have bacterial infections will have an increased risk of treatment failure and poor outcomes. Study design: This research will be conducted in three separate but complementary workstreams: Workstream 1 will include secondary analysis of data collected as a part of the Procalcitonin Evaluation of Antibiotic use in COVID-19 Hospitalised patients (PEACH) study (ISRCTN66682918) to determine how penicillin allergy impacts on antibiotic use and clinical outcomes in patients admitted with COVID-19. The PEACH study was a multi-centre, retrospective, observational, cohort study using patient-level clinical data which investigated whether the use of procalcitonin testing, to guide antibiotic prescribing, safely reduced antibiotic use amongst hospitalised patients with COVID-19 during the first wave of the pandemic using routinely collected patient institutional clinical databases and patient medical records. Data were collected in 11 National Health Service (NHS) acute hospital Trusts and Health Boards in England and Wales, and data in a pseudo-anonymised format was received from the Cardiff Clinical Trials Unit who were the data controllers for the PEACH study. Workstream 2 will compare the oral resistome of patients with and without penicillin allergy. Metagenomic and metatranscriptomic analysis will be used for resistome assessment. Workstream 3 will determine the feasibility of investigating if antibiotic resistance genes are lost after removal of an incorrect penicillin allergy record. This workstream will recruit patients enrolled in the Allergy Antibiotics and Microbial Resistance (ALABAMA) trial (NCT04108637), which is a randomised control trial (RCT) designed to assess the effect of removing incorrect penicillin allergy records on health outcomes. Participants are randomised to either usual care or the intervention group where they receive a novel penicillin allergy assessment pathway (PAAP), if patients in the intervention group are found to be not allergic to penicillin, their allergy label is subsequently removed. Patients recruited to this workstream will be followed up as per the ALABAMA protocol but will also be required to provide baseline and follow up (\> 6 months after enrolment or allergy testing) saliva +/- stool samples. Metagenomic and metatranscriptomic analysis will be used for resistome assessment.