Is the reduced primary care use of broad-spectrum antibiotics resulting in reduced antimicrobial resistance: a population-based ecological study

Problem

Antimicrobial resistance (AMR) is considered one of the greatest threats to public health of modern times. Seventy four percent of all NHS antibiotics are prescribed by GPs and nurses in primary care, making primary care prescribing a key contributor to AMR. The recent NHS England 2013/2014 quality premium award incentivised primary care Clinical Commissioning Groups to reduce overall prescribing and limit the proportion of broad-spectrum antibiotics (co-amoxiclav, cephalosporins and quinolones, the majority of which are prescribed for UTI) to within 10% of total prescribing. Public Health England recently reported a decline of 4.5% in overall antibiotic prescribing between 2012 and 2015. This study will investigate if this reduction in overall and broad spectrum antibiotic use has resulted in changes in urinary isolate AMR rates.

Approach

Antimicrobial susceptibility data was collected from Bristol Royal Infirmary (BRI) and Southmead Microbiology Laboratories for all community-acquired urinary tract infections caused by Escherichia coli between 2013 and 2016. Antimicrobial prescribing data was collected from NHS Digital publicly available prescribing data, grouped by primary care practice. Multilevel models will be used to analyse the relationship between practice-level antibiotic prescribing and resistance, with quarterly individual-patient antibiotic susceptibilities nested within primary care practices. Multilevel models will be developed for each tested antibiotic versus prescribing of that antibiotic, as well as for resistance to any antibiotic versus prescribing of any antibiotic and resistance to broad-spectrum antibiotics versus broad-spectrum antibiotic prescribing.

Findings

Overall, 81,081 E. coli UTIs from 90 primary care practices were tested for antimicrobial susceptibilities at BRI, and 71,623 E. coli UTIs from 84 primary care practices were tested at Southmead laboratory. In total, 86% of patients were female and more than 60% were aged >50 years. For E. coli tested at BRI, the overall resistance prevalence against each antibiotic was: amoxicillin 49.59%, cefalexin 8.53%, ciprofloxacin 9.35%, co-amoxiclav 8.70%, nitrofurantoin 1.80% and trimethoprim 34.01%. For E. coli tested at Southmead, the overall resistance prevalence against each antibiotic was: amoxicillin 52.43%, cefalexin 13.91%, ciprofloxacin 13.78%, co-amoxiclav 9.21%, nitrofurantoin 2.77% and trimethoprim 37.33%. There were no significant year-on-year differences in resistance prevalence for any antibiotic. Overall broad-spectrum resistance prevalence from E. coli UTI isolates tested at BRI and Southmead were 17.79% and 19.18%, respectively.Antibiotic prescribing data and multilevel modelling analyses will be presented at the conference.

Consequences

Although the association between antibiotic use in primary care and antibiotic resistance has been well described in previous literature, there is limited evidence linking changes in antibiotic prescribing with changes in antibiotic resistance, especially at a primary care practice level. This study will provide more up to date information regarding the association between antibiotic prescribing and resistance in primary care, which in turn could encourage clinicians and policymakers to promote more prudent antibiotic use.