Escherichia coli and Salmonella spp. isolated from Australian meat chickens remain susceptible to critically important antimicrobial agents

Autoři: Sam Abraham aff001;  Mark O’Dea aff001;  Shafi Sahibzada aff001;  Kylie Hewson aff002;  Anthony Pavic aff003;  Tania Veltman aff004;  Rebecca Abraham aff001;  Taha Harris aff003;  Darren J. Trott aff004;  David Jordan aff005
Působiště autorů: Antimicrobial Resistance and Infectious Disease Laboratory, Murdoch University, Murdoch, Western Australia, Australia aff001;  Australian Chicken Meat Federation, Sydney, New South Wales, Australia aff002;  Birling Avian Laboratories, Bringelly, New South Wales, Australia aff003;  Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia aff004;  New South Wales Department of Primary Industries, Wollongbar, New South Wales, Australia aff005
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article


The World Health Organisation has defined “highest priority critically important antimicrobials” (CIAs) as those requiring the greatest control during food production. Evidence demonstrating that restricted antimicrobial usage prevents the emergence of resistance to CIA’s amongst pathogenic and commensal organisms on a production system-wide scale would strengthen international efforts to control antimicrobial resistance (AMR). Therefore, in a designed survey of all major chicken-meat producers in Australia, we investigated the phenotypic AMR of E. coli (n = 206) and Salmonella (n = 53) from caecal samples of chickens at slaughter (n = 200). A large proportion of E. coli isolates (63.1%) were susceptible to all tested antimicrobials. With regards to CIA resistance, only two E.coli isolates demonstrated resistance to fluoroquinolones, attributed to mutations in the quinolone resistance-determining regions of gyrA. Antimicrobial resistance was observed for trimethoprim/sulfamethoxazole (8.7%), streptomycin (9.7%), ampicillin (14.1%), tetracycline (19.4%) and cefoxitin (0.5%). All Salmonella isolates were susceptible to ceftiofur, chloramphenicol, ciprofloxacin, colistin, florfenicol, gentamicin and tetracycline. A low frequency of Salmonella isolates exhibited resistance to streptomycin (1.9%), ampicillin (3.8%), and cefoxitin (11.3%). AMR was only observed among Salmonella Sofia serovars. None of the Salmonella isolates exhibited a multi-class-resistant phenotype. Whole genome sequencing did not identify any known resistance mechanisms for the Salmonella isolates demonstrating resistance to cefoxitin. The results provide strong evidence that resistance to highest priority CIA’s is absent in commensal E. coli and Salmonella isolated from Australian meat chickens, and demonstrates low levels of resistance to compounds with less critical ratings such as cefoxitin, trimethoprim/sulfamethoxazole, and tetracycline. Apart from regulated exclusion of CIAs from most aspects of livestock production, vaccination against key bacterial pathogens and stringent biosecurity are likely to have contributed to the favorable AMR status of the Australian chicken meat industry. Nevertheless, industry and government need to proactively monitor AMR and antimicrobial stewardship practices to ensure the long-term protection of both animal and human health.

Klíčová slova:

Antimicrobial resistance – Chickens – Livestock – Meat – Poultry – Salmonella – Salmonella typhimurium – Tetracyclines


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2019 Číslo 10
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