A survey on antimicrobial resistant Escherichia coli isolated from unpasteurised cows’ milk in Northern Ireland

Antimicrobial resistance (AMR) limits the effectiveness of disease treatment for human and animals (WHO 2015). Food-producing animals (FPAs) can act as a reservoir of resistant zoonotic bacteria (Smith 1969, Shooter and others 1970, Levy and others 1976, Bertrand and others 2006, Skockova and others 2015).Commensal Escherichia coli are part of the intestinal flora of human and animals (Heymann 2014; Merck 2010). However, they can be pathogenic and have been responsible for the majority of human bacteraemia cases in the UK (DARC-ARHAI 2012; Paterson and Bonomo 2005, PHE 2015). E coli is recognised as a potential reservoir of AMR genes in food products and animals; indeed, the degree of resistance exhibited by commensal E coli is also considered a sentinel of resistance levels in other Gram-negative bacteria in the gut flora (ECDC 2016, VMD 2014b, 2015). Thus, since 2013, EU Member States have been obliged to monitor for AMR in indicator bacteria such as E coli in livestock and food (EU-Commission 2013).Although resistant E coli , including those expressing extended-spectrum beta lactamases (ESBL), have been isolated from several FPAs such as poultry (Costa and others 2009, Dierikx and others 2013, ECDC 2016; Parker and others 2016, VMD 2014b), cattle (Duse and others 2015a, b, Saini and others 2012, VMD 2014b), pigs (DARC 2004; VMD 2015) and food such as meat (ECDC 2016), currently there is a limited number of surveys of other important components of the human diet, such as milk (Nagy and others 2015, Skockova and others 2015).The average UK citizen consumes around 224 l of milk per year (Dairy-Council 2016). If AMR bacteria were present in this foodstuff, it may constitute an important exposure risk. A …