Escherichia coli is a commensal bacteria found in the gastrointestinal tract of warm-blooded animals. By aquisition of various virulence factor genes it can colonise other tissues and organs, thus becoming pathogenic. Additionally, the number of antimicrobial resistant strains is steadily increasing in the last two decades. The most concerning β-lactamases are ESBLs, AmpC and carbapenemases. The aim of our study was to determine the presence, distribution and the spread of ESBL and/or AmpC-producing E. coli in and among animals from selected poultry farms. Strains phenotypically positive for ESBL and AmpC enzymes were isolated from different poultry farms in Slovenia, have been grouped into 39 different clonal groups based on ERIC-PCR. Sixty-four isolates that were confirmed as ESBL- and AmpC-positive by molecular approaches, were further assigned to phylogenetic groups and screened for presence of different resistance and 20 virulence genes. The majority of the isolates (40,3 %) carried the blaSHV-12 allele and only 29,2 % the blaCMY-2 allele. Twenty-eight were positive for presence of qnrS gene. Twenty-six of them also carried the blaSHV-12 allele. Several conjugation experiments revealed a different low conjugation frequencies (10-4-10-8), depending on the donor strain and the selected resistotype. Restriction profile analysis of plasmid DNA from transconjugants confirmed the presence and more frequently vertical spread of different plasmids encoding AmpC- and CTX-M- β-lactamase genes and the predominantly horizontal spread of 2, almost identical, plasmids encoding blaSHV-12 and qnrS genes in and between poultry farm included in the survey.
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