ESBL- and AmpC-producing Escherichia coli from legally and illegally imported meat: Characterization of isolates brought into the EU from third countries

Multiresistant Enterobacteriaceae producing extended-spectrum β-lactamases (ESBL) constitute a serious healthcare concern. Contaminated meat and meat products have been suggested as a major transmission route for these strains in the population. In this study, 36 ESBL-/AmpC-producing Escherichia (E.) coli isolates recovered from meat products imported into the EU from third countries (non-EU countries), both legally and illegally, were examined with regard to their antibiotic resistance profiles, virulence-associated genes and their genetic relatedness. The isolates were characterized by antibiotic susceptibility testing, multilocus sequence typing, macrorestriction analysis, microarray analyses and additional PCR assays. The most prevalent ESBL gene among the isolates was blaCTX-M-2 (n=15), followed by the AmpC β-lactamase gene blaCMY-2 (n=8). The remaining isolates carried genes belonging to CTX-M groups 8, 1 or 9, or blaSHV-12. This distribution differs from the genotypes typically detected in meat-associated isolates of European origin. Most isolates showed additional phenotypic resistances and genes conferring resistance to further antimicrobial agents were detected through microarray analysis. Most commonly observed were resistances to tetracycline, sulfamethoxazole/trimethoprim, and gentamicin. A genotype conferring multidrug resistance to 3 or more classes of antimicrobials could be observed in 33 isolates (91.7%). Most isolates carried at least one gene associated with virulence and one isolate could be identified as an enteropathogenic E. coli, indicating a potential risk to consumers' health. Molecular typing results revealed a genetic variety among the isolates. The most common multilocus sequence types were ST101 and ST117, represented by three isolates each. One isolate belonged to ST131 and three novel sequence types could be identified among three isolates (ST7509, ST7602, ST7845). Group D was the most prevalent phylogenetic group, which was represented by 18 isolates. Overall, the results of this study show that imported meat products can constitute a source for locally uncommon lineages of multidrug resistant and virulent ESBL-producing E. coli and can thereby facilitate their dissemination in Europe.