An insight into Antimicrobial Resistance Screening in Veterinary Microbiology Diagnostic Laboratories in the United Kingdom ​

Introduction: Antimicrobial resistance (AMR) is a globally relevant public health priority requiring coordinated One Health responses. In recent years, the emergence of novel AMR phenotypes and increasing AMR trends in bacteria from companion animal and horses have become an apparent concern worldwide; nevertheless, limited national resistance monitoring programmes in Europe systematically collect and analyse data from companion animal and equine infections. In the UK, private veterinary microbiology diagnostic laboratories hold valuable AMR data, however, there is a lack of alignment in the methodologies used by diagnostic laboratories to generate these data. Gap Statement: Substantial knowledge gaps exist in the current landscape of veterinary microbiological diagnostic testing approaches for AMR in companion animals and horses. The VetCLIN AMR initiative aims to engage with UK veterinary diagnostic laboratories to capture methods used for generating routine antimicrobial susceptibility data which impacts on national AMR surveillance. Aim: To perform a UK-wide survey of veterinary laboratories processing companion animal and equine specimens evaluating the standard practices used for microbiology testing with a focus on AMR screening. Methodology: An online survey targeting veterinary diagnostic laboratories in the UK processing clinical specimens from companion animals and horses.

Twenty-one (n=21) UK veterinary microbiology laboratories responded, comprising commercial (10/21), university (7/21), and in-house veterinary practice/hospital laboratories (4/21). Methodological heterogeneity in bacterial identification, antimicrobial susceptibility testing (AST), AMR detection and reporting was identified across UK veterinary laboratories. Overall, the laboratories’ preferred AST method was minimum inhibitory concentration (43%), with most of these using the VITEK-1/VITEK-2 system (52%). A combination of CLSI and EUCAST standards was most used by these laboratories (62%) for AST interpretation, with limited adoption of the lower clinical breakpoints for Enterobacterales (amoxicillin–clavulanic acid and fluoroquinolones). Detection of AMR mechanisms was focused on clinical guidance and phenotypes commonly encountered among companion and equine isolates, such as screening for methicillin resistance in staphylococci (95%) and extended-spectrum beta-lactamase (ESBL)-production in Enterobacterales (48%). Up to 30% of UK veterinary laboratories screened for carbapenem resistance in Gram-negative bacteria. Detected AMR phenotypes are infrequently characterised or referred to reference laboratories and, in the case of carbapenem resistance, these are often not reported to clinicians.

This study identified a variety of workflows used by veterinary diagnostic laboratories for bacterial identification, methodologies and interpretative criteria used for performing and reporting AST, as well as AMR screening approaches. Several gaps hindering national AMR surveillance in dogs, cats and horses in the UK have become evident. Strengthening surveillance capacity should prioritise consistent screening and characterisation of AMR mechanisms such as ESBL and carbapenemase production, to enable effective responses to AMR emergence and spread in companion animals and equine clinical infections. - Received: - Version Posted: Funding - Veterinary Medicines Directorate (Award NA) - Principal Award Recipient: Dorina Timofte