Measures to reduce ESBL-producing Escherichia coli in pig farms : a literature review

Escherichia coli (E. coli) is a common bacterial species in the intestines of humans and animals. Some kinds of E. coli can act as pathogens and most of them are considered zoonotic. Antimicrobial resistance has increased in the last years and is an important topic in the concept of One Health. Extended-spectrum β-lactamases (ESBL) producing E. coli are bacteria which are able to limit the effect of β-lactam antibiotics. Restricting the options of antibiotics, ESBL producing E. coli are furthermore able to limit the effect of the cephalosporins of the 3rd and 4th generation which are considered critically important antimicrobials by the WHO. In this literature review the data bases Scopus, PubMed and Google Scholar were scanned for research on ESBL producing E. coli regarding potential risk factors and measures to reduce them in pig farms. We were able to find that the prevalence in pigs differs from 1.2 % to 85 % while the prevalence in humans was described from 6 % up to 86 % in the current literature. Although evidence is still inconclusive it has been shown that a lack of external biosecurity measures like no hygiene lock at the entrance, visitors and pets on the farm correlate with a higher prevalence of ESBL producing E. coli in pigs. Internal biosecurity measures including all-in-all-out systems and pest control by specialists correlate with lower prevalence of ESBL producing E. coli in pigs. One of the most important factors influencing resistance is antibiotic usage. This review revealed that the use of cephalosporins and group treatments seem to have a highly negative impact on the occurrence of ESBL producing E. coli. Measures that could be implemented on pig farms to reduce the prevalence of ESBL producing E. coli are a radical decontamination, bacteriophages and low zinc diets.