Epidemiology of Escherichia coli bloodstream infection antimicrobial resistance trends across South West England during the first 2 years of the coronavirus disease 2019 pandemic response

Objectives Between 2016-19, the proportion of Escherichia coli bloodstream infection (BSI) with resistance to at least one antibiotic increased nationally. Public health interventions implemented in response to the coronavirus disease 2019 (COVID-19) pandemic changed population contact patterns and healthcare systems, with consequent effects on epidemiological trends of numerous pathogens. We investigated the impact of COVID-19 restrictions on epidemiological trends of E. coli BSI antimicrobial resistance (AMR) across South West England. Methods We undertook a retrospective ecological analysis utilising routine surveillance data of E. coli BSI cases reported to the UK Health Security Agency between 2016-2021. We analysed AMR trends for antimicrobial agents including amoxicillin-clavulanate, ciprofloxacin, piperacillin-tazobactam, gentamicin, third-generation cephalosporins and carbapenems before and after implementation of COVID-19 restrictions (23/03/2020) using Bayesian segmented regression. Results We identified 19,055 cases. 50.2% were male. Median age was 76 (interquartile range 65-85). Piperacillin-tazobactam (-2.90% 95% Highest Density Interval (HDI) -4.51%, -0.48%) and ciprofloxacin (-2.40% 95% HDI -4.35%, 0.48%) resistance demonstrated immediate step changes at implementation of COVID-19 restrictions. Gentamicin (Odds Ratio (OR) 0.92 95% HDI 0.76, 1.12) and third-generation cephalosporins (OR 0.95 95% HDI 0.80, 1.14) exhibited decreasing annual resistance trends following implementation of COVID-19 restrictions, with moderate evidence for a lower OR after restrictions as compared to the period before (gentamicin Bayes Factor (BF)=5.10, third-generation cephalosporins BF=6.67). Conclusions COVID-19 restrictions led to abrupt and longer-term changes to E.coli BSI AMR. The immediate effects suggest altered transmission, while changes to resistant E. coli reservoirs may explain trend effects.