Markers of antimicrobial resistance in the bovine gut with relevance to human and veterinary medicine

Antimicrobial Resistance poses a large threat to both human and animal healthcare. Antibiotics used on farm are the same or very similar to those used in human healthcare, which leads to concerns over the development of resistant organisms. The aim of this study was to create resistance profiles of isolates from bovine gut and environment on farms, from organisms of medical and veterinary importance. Three dairy farms were enrolled for the study. Samples were taken that represented the bovine gut and environment. Environmental samples were taken from similar locations across all three farms. The antibiograms were produced using the SIRscan 2000 and MICs were calculated to begin identifying values for antibiotics that do not have clinical breakpoints in veterinary medicine. Amongst the three farms enrolled, 807 strains were isolated, with the most prevalent resistance being seen against Tetracycline. Many of the organisms were multi-class resistant. Escherichia coli had high MIC values against Tetracyclines that were greater than or equal to 64mg/l, correlating with the high levels of resistance seen. All farms showed resistance to multiple antibiotics in different classes, the profiles varied between the bovine gut and environment on farm and amongst all three farms. This study showed a snapshot of the resistance profiles that can be found. Longitudinal studies would provide data as to how resistance changes over time and as exposure to antibiotics changes also. By providing information as to what resistance is routinely seen on farm and how resistance evolved over time. A better understanding will be gained with greater detail and a clearer view of the effects of antibiotic use in the cattle industry.