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Home » Archive » 2023

TDK conference 2023

Antibiotic susceptibility and metagenomic analysis of multiresistant Enterococcus bacteria strains of poultry origin
Horváth Ákos - year 5
University of Veterinary Medicine Budapest, Department of Pharmacology and Toxicology
Supervisors: Ádám Kerek, Patrik Mag

Abstract:

One of the major challenges of the 21st century is the growing prevalence of antibioticresistant pathogens. These pathogens include certain Enterococcus species, which are a growing concern in animal and public health due to their antibiotic-resistant strains. In our study, we pre-screened a total of 969 samples from Hungarian flocks of domestic chickens and turkeys with approved substances for poultry, and further filtered the samples down to 218 by antibiotic susceptibility testing for substances of importance in human health. The resistance profiles of isolates showing resistance to linezolid and vancomycin, which are important in human health, were mapped by metagenomic studies.

In our study, 196 (89.9%) of the 218 pre-screened samples were classified as multidrugresistant (MDR). Of these 196 isosolates, 8 were presumptively extensively drug-resistant (XDR) and 1 was presumptively pandrug-resistant (PDR) based on the criteria we considered. Among the substances approved for use in poultry, resistance rates varied between 97.7% and 42.2%. Among these agents, enrofloxacin was found to be the most effective antibiotic and linkomycin the least effective. Among the human agents, imipenem was the most effective, with only 7.3% of the samples tested being resistant. 15.6% of the samples tested were resistant to vancomycin and 19.3% to linezolid. Based on the European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cut-off values, 36.2% of the samples were in the non-wild-type group against linezolid and 71.1% against vancomycin. For metagenomic analysis, 42 MDR strains resistant to vancomycin and/or linezolid were selected. Among them, genes specifically encoding resistance to vancomycin were found in five strains and genes encoding resistance to peptide antibiotics in 14 strains. Phenotypically, 18 strains showed resistance to linezolid, but no genes specifically encoding linezolid resistance were found in the metagenomic analysis.

Our research supports the spread of resistant Enterococcusstrains in the sector, as 89.9% of the 218 pre-filtered isolates were found to be MDR pathogens. The majority of the substances authorised for poultry showed resistance above 50%, while only azithromycin (62.4%) showed such a high level of resistance among human products. The values against vancomycin and linezolid are of concern as these active substances are not used at all in livestock medicine.



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