There has been a decline of antimicrobial-resistant E. coli but not Campylobacter in chicken based on surveys by the Food Standards Agency (FSA).

Two annual surveys tested fresh chicken sold in the United Kingdom, with one looking at certain antimicrobial-resistant (AMR) E. coli, and the other at AMR Campylobacter. Results are from 2017 to 2018. A previous study looked at beef and pork.

Use of antibiotics is important in treating infections and preventing disease in animals and humans. However, the overuse or misuse of antimicrobials in animal husbandry and healthcare settings has been linked to emergence and spread of microorganisms which are resistant to them, making treatment ineffective and posing a risk to public health.

Paul Cook, the FSA’s science lead in microbiological risk assessment, said: “While there is evidence that AMR bacteria are present on chicken sold in the U.K., it is encouraging to see the levels holding steady and even reducing. The risk of getting AMR-related infections through eating or preparing contaminated meat remains very low as long as you follow good hygiene and cooking practices.”

AMR E. coli results
In total, 309 samples of chicken were collected and tested for E. coli between January and December 2018 from 10 supermarket chains. They included whole chicken, chicken breast and other cuts like quarters, legs, thighs and drumsticks. Two samples originated from Poland but all others came from the U.K.

The proportion of samples positive for Extended Spectrum Beta-lactamase (ESBL)-producing E. coli fell from 65.4 percent in 2013/14 to 29.7 percent in 2016 and 8.4 percent in 2018.

No E. coli samples were resistant to carbapenem. A total of 13 samples grew on agar with the antibiotic colistin but none were positive for plasmid-mediated colistin resistance genes mcr-1, mcr-2 or mcr-3.

Samples positive for AmpC-producing E. coli fell from 16.3 percent in 2016 to 5.2 percent in 2018. The proportion of samples that grew on agar containing cefotaxime also decreased in 2018 to 13.6 percent compared to 45.1 percent in 2016.

The proportions of chicken samples with E. coli with AmpC+ESBL and ESBL-phenotype were higher for skin off rather than skin on samples.

Forty-two E. coli samples were resistant to cefotaxime, a third generation cephalosporin. Of these, 23 expressed ESBL-phenotype resistance, 16 were found to express AmpC-phenotype resistance and 3 expressed both ESBL- and AmpC-phenotype resistance.

Isolates with a combined ESBL+AmpC-resistance phenotype were on average resistant to more antimicrobials. No isolates were resistant to the antimicrobials azithromycin, meropenem, temocillin or tigecycline.

“This reduction in the level of antimicrobial resistant E. coli on chicken meat since 2013/14 may be linked to the banning by the British Poultry Council of the use of third and fourth generation cephalosporins in flocks used for poultry meat production in the U.K. in 2012 as part of antimicrobial stewardship,” according to the report.

AMR Campylobacter findings
The other survey tested 1,769 samples of whole, U.K.-produced, fresh chicken during August 2017 to July 2018 for Campylobacter.

A total of 393 of the Campylobacter isolates collected from 392 retail chicken samples were tested for AMR out of 1,114 positive samples. A total of 263 isolates came from major retailers and 130 from smaller shops. This included 328 Campylobacter jejuni and 65 Campylobacter coli isolates.

The level of antimicrobial-resistant isolates were similar to what was reported in the previous survey from August 2016 to July 2017. The finding of AMR Campylobacter isolates on chickens means it is important to handle birds hygienically and cook them thoroughly to reduce public health risk, according to researchers.

Ciprofloxacin resistance was identified in 52 percent of the Campylobacter jejuni isolates and just under half of the Campylobacter coli isolates. Two Campylobacter jejuni and two Campylobacter coli isolates were resistant to erythromycin and 52 percent of Campylobacter jejuni and 60 percent of Campylobacter coli isolates to tetracycline.

None of them were resistant to gentamicin whereas 2 percent of Campylobacter jejuni and 9 percent of Campylobacter coli were resistant to streptomycin.

Multi-drug resistance (MDR), so resistance to three or more unrelated antimicrobial classes, was found in six Campylobacter coli and five Campylobacter jejuni isolates. A higher proportion of Campylobacter coli isolates showed MDR but the reason for this is not well understood.

The percentages of fluoroquinolone-resistant isolates were similar to previous survey years but higher compared to data from earlier studies. The proportion of tetracycline-resistant Campylobacter jejuni was significantly lower in this study compared to past data.

Differences in levels of ciprofloxacin- and tetracycline-resistance in isolates from standard, free range and organic birds were examined with no significant findings.

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