Antimicrobial resistance levels revealed in pork and chicken

The report, called ‘Surveillance Study of Antimicrobial Resistance in Bacteria Isolated from Chicken and Pork Sampled on Retail Sale in the United Kingdom’,​ revealed that AMR was detected in a proportion of all the types of bacteria examined, with the resistance to the most clinically important drugs more prevalent in chicken isolates than pork.

The study was conducted after a systematic review of AMR in the food chain by the Food Standards Agency, which concluded that there was a lack of data on AMR prevalence in British-produced food.

A key recommendation was to address these gaps by developing research and surveillance to monitor AMR levels in foodborne pathogens and commensal bacteria in poultry and pork meat.

The surveillance study was carried out over a two-month period to determine the prevalence of AMR in bacteria isolated from fresh/frozen chicken (whole or portions) and fresh pork mince on retail sale in the UK.

Between the beginning of September and end of October 2017, 339 samples of raw chicken (whole or portions) and 342 samples of raw pork mince from retailers in England, Wales, Scotland and Northern Ireland were collected. Samples included both domestically produced and imported meats.

These were tested for Escherichia coli ​(including ESBL-producing E.coli), Klebsiella,​ and Enterococci​, as well as Campylobacter​ in the case of chicken samples, and Salmonella ​in pork.

Salmonella ​was only detected in five of the 342 (1.5%) of pork mince samples. Four of the positive samples originated from the same processing plant and were resistant to ampicillin and tetracycline, and one to chloramphenicol.

Campylobacter ​was detected in 85 of the 339 (25%) of all chicken samples (fresh and frozen). Overall, under half of Campylobacter ​isolates were resistant to ciprofloxacin (40.6%) and nalidixic acid (46.5%), whilst 61.4% showed resistance to tetracycline.

E.coli ​was detected more frequently in chicken samples (165 of the 339; 49%) than in pork mince (35 of the 342; 10%). According to the report, higher percentages of E.coli ​were detected with resistance to fluoroquinolones (ciprofloxacin and nalidixic acid) from chicken than from pork, but higher percentages of E.coli ​were detected with resistance to chloramphenicol and tetracycline in pork compared to chicken.

Enterococci​ were isolated more frequently from chicken samples (180/339; 53%) than from pork mince samples (103/342; 30%). In the 298 isolates tested, resistance was rare, with only three (1%) exhibiting vancomycin resistance and one (0.3%) showing resistance to teicoplanin.

Klebsiella ​species were detected more frequently in pork mince (127 of the 342; 37%) than chicken (22 of the 339; 6.5%). Of 85 Klebsiella ​isolates examined, rates of resistance were lower than observed in E.coli​, with the exception of ampicillin, to which Klebsiella ​species are intrinsically resistant.

The report concluded: “The risk of acquiring AMR related bacterial infections from these foods is very low provided that they are cooked and handled hygienically​.”

The study was conducted after the Food Standards Agency identified antimicrobial resistance (AMR) in Campylobacter ​from chickens and Salmonella ​in pork as a surveillance priority following the AMR systematic review published in 2016 (Food Standards Agency, 2016).