Detection of extended‐spectrum β‐lactam, AmpC and carbapenem resistance in Enterobacteriaceae in beef cattle in Great Britain in 2015

Aims: This study investigated the occurrence and genetic diversity of Enterobacteriaceae with Extended-Spectrum Beta-Lactamase (ESBL), AmpC and carbapenemase mediated resistance in British beef cattle, and related risk factors. Methods and Results: Faecal samples (n=776) were obtained from farms in England & Wales (n=20) and Scotland (n=20) in 2015. Isolates from selective agars were identified by MALDI ToF mass spectrometry. Selected isolates were characterised by multiplex PCR (blaCTX-M, blaOXA, blaSHV and blaTEM genes), whole genome sequencing (WGS), MICs and PFGE. None of the faecal samples yielded carbapenem resistant E. coli. Ten (25%) of the farms tested positive for ESBL-producing CTX-M Enterobacteriaceae, fifteen (37.5%) of the farms were positive for AmpC phenotype E. coli and none were positive for carbapenem resistant E. coli. WGS showed a total of 30 different resistance genes associated with E. coli, Citrobacter and Serratia from ESBL agars, and co-location of resistance genes with blaCTX-M1. Buying bulls and bringing in fattening cattle from another farm were identified as significant risk factors for positive samples harbouring CTX-M Enterobacteriaceae or AmpC phenotype E. coli respectively. Conclusions: Beef cattle on a proportion of farms in GB carry ESBL-producing Enterobacteriaceae. Factors, such as operating as a closed herd, may have an important role in reducing introduction and transmission of resistant Enterobacteriaceae. The results indicate management factors may play an important role in impacting ESBL prevalence. In particular, further study would be valuable to understand the impact of maintaining a closed herd on reducing the introduction of resistant Enterobacteriaceae. Significance and Impact of the study: This is the first study showing the presence of ESBL-producing Enterobacteriaceae in British beef cattle.