ABSTRACT
Background and Aim: Although Enterococcus faecalis and Enterococcus faecium are common members of human and animal gut microbiota, their resistance to different antimicrobials makes them important pathogens. Multidrug-resistant enterococci often contaminate foods of animal origin at slaughterhouses. The World Health Organization and the World Organization for Animal Health recommend including animal-derived enterococci in antimicrobial resistance (AMR) monitoring programs. This study aimed to fill a literature gap by determining the current AMR prevalence of E. faecalis and E. faecium from different food-producing animals in Russia. Materials and Methods: Samples of biomaterial were taken from chickens (n=187), cattle (n=155), pigs (n=49), turkeys (n=34), sheep (n=31), and ducks (n=31) raised at 28 farms in 15 regions of Russia. Isolates of E. faecalis (n=277) and of E. faecium (n=210) (487 isolates in total; 1 isolate per sample) were tested for resistance to 12 antimicrobials from 11 classes using the broth microdilution method. Three criteria were used for the interpretation of minimum inhibitory concentration: Epidemiological cutoff values (ECOFFs) from the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) clinical breakpoints. The AMR cloud online platform was used for data processing and statistical analysis. Results: A difference of >10% was found between E. faecalis and E. faecium resistance to several antimicrobials (erythromycin, gentamycin, tetracycline, chloramphenicol, ciprofloxacin, and streptomycin). In total, resistance to most antimicrobials for enterococci isolates of both species taken from turkeys, chicken, and pigs was higher than cattle, sheep, and ducks. The highest levels were found for turkeys and the lowest for ducks. Among antimicrobials, resistance to bacitracin and virginiamycin was 88-100% in nearly all cases. High levels of clinical resistance were found for both bacteria species: Rifampicin (44-84%) from all animals, tetracycline (45-100%) from poultry and pigs, and erythromycin (60-100%), ciprofloxacin (23-100%), and trimethoprim-sulfamethoxazole (33-53%) from chickens, turkeys, and pigs. No vancomycin-resistant isolates were found. Most isolates were simultaneously resistant to one-three classes of antimicrobials, and they were rarely resistant to more than three antimicrobials or sensitive to all classes. Conclusion: Differences in resistance between enterococci from different farm animals indicate that antimicrobial application is among the crucial factors determining the level of resistance. Conversely, resistance to rifampicin, erythromycin, tetracycline, and ciprofloxacin found in enterococci from farm animals in our study was notably also found in enterococci from wild animals and birds. Our results may be partly explained by the intrinsic resistance of E. faecium and E. faecalis to some antimicrobials, such as trimethoprim/sulfamethoxazole and bacitracin.
ABSTRACT
BACKGROUND AND AIM: Commensal Escherichia coli is an important indicator of antimicrobial resistance (AMR) in animals and food of animal origin. Therefore, it was recommended by the World Health Organization and OIE for inclusion in resistance surveillance programs. At the same time, the data on E. coli isolates from animals in Russia are scarce. The aim of this work was to determine the current prevalence of resistance and genetic markers of non-pathogenic commensal E. coli collected from major food-producing animals (poultry, pigs, and cows) in different regions of Russia and to compare these data with data from other countries to prioritize antimicrobials for limiting their use according to the National Action Plan. MATERIALS AND METHODS: Samples (n=306) were collected from biomaterial of chicken, turkey, cows, and pigs raised on 11 farms in the European part of Russia, Siberia, and North Caucasus. Isolates (n=306) of E. coli were tested for resistance to 11 antimicrobials from ten classes using the broth microdilution method. MICs were interpreted against EUCAST microbiological and clinical breakpoints. For data analysis and statistical processing, the AMRcloud online platform was used. The data are presented in comparison with other countries. RESULTS: In Russia, higher levels of microbiological and clinical resistance of E. coli to critically important antimicrobials, including colistin, cefotaxime, and ciprofloxacin, were found compared to other countries, especially in poultry: About 30% of isolates from chicken were resistant to colistin, 8% to cefotaxime, and 88% to ciprofloxacin according to EUCAST ECOFFs. Only 10% of isolates from cows were resistant to cefotaxime. About 47% of isolates of E. coli from chicken had a moderate relative resistance for ampicillin and 56% for tetracycline. For most antimicrobials, isolates from cows demonstrated a lower resistance than isolates from poultry and pigs. All tested isolates from chicken, turkey, and pigs showed a simultaneous microbiological resistance to at least three classes of antimicrobials. No pan-resistant isolates were found. CONCLUSION: High levels of AMR of commensal E. coli from poultry, especially for critically important drugs, are a matter of concern and should be taken into account when choosing antimicrobials to be restricted for use in animal husbandry according to the National Action Plan.
