Photo: Sebastian Kaulitzki/shutterstock
Worldwide, antibiotics are used in animal production at therapeutic levels for the treatment of infections and for growth promotion or prophylaxis. The disadvantage of antibiotics is the emergence and spread of resistant bacteria. Resistant bacteria have become a major concern for both animal health and the public as human medicine is running out of antibiotics that are still effective in treating certain infections.
Antibiotic use in animal production has been identified as a risk factor in the development of antibiotic resistant bacteria that can be transferred to humans via several routes. These include the consumption of animal products, exposure to resistant microorganisms from contact with animals, and the contamination of ground and surface waters by wastes containing antimicrobials and resistant microorganisms.
Exposure to antibiotics not only increases the level of antibiotic resistance among bacteria belonging to the normal intestinal flora of animals but also among pathogenic bacteria. Where high levels of resistant pathogenic bacteria are present, antibiotic treatments may no longer be effective against pathogens.
E. coli resistance in swine
Surveillance and monitoring studies on antimicrobial resistance provide information about the occurrence of resistances in pigs in different parts of the world. E. coli resistance in swine was described in the Austrian Resistance Report AURES, a yearly report published since 2004 on the levels of resistance in humans and the veterinary sector.
To date, a total of about 160 digesta samples from the large intestine of swine from 30 farms in Austria have been analyzed for E. coli. Tests for antimicrobial susceptibility to different antibiotics were conducted. The microbiological resistance of E. coli using epidemiological cut-off values is shown in Figure 1. Epidemiological cutoff values are determined on the basis of the distribution of minimal inhibitory concentration for an antibiotic and a bacterial species. The cut-off values for different antibiotics are presented by the European Committee on Antimicrobial Susceptibility Testing (EUCAST).
Figure 1. Microbiological resistance of E. coli to different antibiotics in Austria>