Purpose: The purpose of this study was to investigate the antibiotic resistance patterns of E. coli and Salmonella isolates from a vertically integrated poultry producing region in Australia.
Methods: E. coli and Salmonella were isolated from breeder and broiler farms (drag swabs, n = 41) and from corresponding dressed carcasses (whole carcass rinses, n = 30) at point of pack, using standard cultural techniques. The antimicrobial sensitivities of the isolates were determined using the Gram-negative veterinary and human antibiotic panels for the Vitek 2 system. The data was analyzed and compared to international studies to identify any significant antibiotic resistance patterns seen in this production area.
Results: Seventy-five percent of E. coli isolates (n = 8) were sensitive to all antibiotics tested, with one isolate resistant to both ampicillin and piperacillin, and one isolate tetracycline-resistant. Forty percent of Salmonella isolates from breeder (n = 5) and broiler (n = 10) flocks were sensitive to all antibiotics. However, 53% were resistant to piperacillin, 47% ampicillin-resistant, 40% nitrofurantoin-resistant, and 13% tetracycline-resistant. The majority of Salmonella isolates from carcass rinsates were primarily Salmonella subsp. II ser 1,4,12,27:b:[e,n,x], with 83% resistant to ampicillin, piperacillin and nitrofurantoin.
Significance: The low levels of resistance indicate that careful antibiotic use in the Australian poultry industry is having little impact upon circulation of antimicrobial resistance. Additionally, the pilot study data will facilitate a nationwide survey to assess the current prescribing practices and compare antimicrobial resistance to global data, thereby reducing the risk of foodborne antibiotic resistance spreading to the general public.