Antimicrobial resistant bacteria in beef production in Australia

Summary

​Australia is one of the world’s most efficient producers of cattle and third largest exporter of beef, exporting 67% of its total beef and veal production in 2012-2013. The supply of Australian beef products into world trade markets is dependent on the capacity of producers to export products that are, upon consumption, unlikely to cause disease or be detrimental to human medicine. Pathogenic STEC (pSTEC) and antimicrobial resistance have been identified as important factors when evaluating the perceived safety of beef products and the risk to human medicine. The group of E. coli collectively referred to as pSTEC include the prototype pSTEC serogroup O157 and six additional serogroups (known as the Big6) O26, O45, O103, O111, O121 and O145. In 2012, the USA introduced regulations that classified the seven serogroups of pSTEC as adulterants of raw non-intact beef products. Similarly, there has been recent pressure to classify specific strains of antimicrobial resistant Salmonella as adulterants in beef products. Australia does not have ongoing multi-focus surveillance programs capable of evaluating the presence of zoonotic pathogens and antimicrobial resistance (AMR) in food production systems and instead conducts relatively short-term intensive surveys to evaluate the industry status. This report details the prevalence of pSTEC and the AMR status of Salmonella, E. coli, and Enterococcus in Australian beef cattle.
This study reports the prevalence of pSTEC and the AMR status of Salmonella, E. coli and Enterococcus from beef cattle groups slaughtered at Australian export registered abattoirs. The results indicate that E. coli O157 remains the dominant pSTEC in Australian cattle with E. coli O26 and E. coli O111 the only other pSTEC serogroups identified. The isolation of pSTEC serogroups O45, O103, O121 and O145 did not occur from any sample and is consistent with previous investigations and suggests that these serogroups are extremely rare in Australian cattle. Nonetheless, the presence of any pSTEC serogroups in cattle represents an ongoing challenge for producers who must continue to adhere to stringent processing guidelines and testing procedures to help ensure contaminated beef products do not enter commerce. Similarly, whilst the AMR data generated by this study suggests that in general beef cattle production practices are likely to have minimal effect on human clinical treatment outcomes there are data that warrant further investigations. It therefore remains necessary to maintain strict guidelines and controls around the use of antimicrobials in food-production animals in Australia and to continually monitor the effects of all antimicrobial use if Australia’s reputation as a supplier of safe and healthy food is to be maintained.