Diversity of CTX-M-1-producing E. coli from German food samples and genetic diversity of the bla CTX-M-1 region on IncI1 ST3 plasmids

Abstract

Antimicrobial resistance to cephalosporins is commonly mediated by extended-spectrum β-lactamases (ESBL) or plasmidic AmpC β-lactamases (pAmpC). In livestock bla is the most frequently detected ESBL-encoding gene. As transmission to consumers through contaminated food is often proposed, this study characterized ESBL/pAmpC-producing E. coli collected from food samples. Therefore, samples from food products of animal origin and vegetables were screened for phenotypically resistant E. coli by selective cultivation. The ESBL genotype was confirmed for 404 isolates with the majority of them (n = 212) harboring the bla gene. PFGE and MLST analyses as well as plasmid characterization were carried out for 89 isolates, selected under epidemiological aspects. In addition, 44 isolates were investigated by whole genome sequencing and/or sequencing of their plasmids on an Illumina Miseq platform. MLST and PFGE indicated a diverse population of CTX-M-1-producing E. coli in German food samples with no spread of single clonal lineages. The majority of the isolates harbored the bla gene on IncI1 plasmids. Frequently, the gene was associated with the ISEcp1 element and located on a ∼100 kb IncI1 plasmid depicting the plasmid multilocus sequence type (ST) 3. The bla gene and its flanking sequences were located within the shufflon of the type IV pilus region in diverse orientations. In conclusion, dissemination of the CTX-M-1 β-lactamase within food samples of animal origin is driven by the transmission of a ∼100 kb large IncI1 ST3 plasmid. Apart from conjugal transfer of IncI1 ST3 plasmids the transmission of the bla gene might be further promoted through mobilization due to its location within a recombination hot-spot of IncI1 plasmids.

ESKAPE Bacteria and Extended-Spectrum-β-Lactamase-Producing Escherichia coli Isolated from Wastewater and Process Water from German Poultry Slaughterhouses

“…CTX-M-1 belongs to the most abundant determinants in ESBL-producing E. coli, which correlates well with prevalence data for bla CTX-M-1 (18.0-69.0%) in isolates from chickens and chicken meat in Germany(89,90). Similar to other studies, E. coli isolates carrying bla SHV-2 , bla SHV-2a and bla TEM-20 were only sporadically detected in chicken and retail chicken meat(91,92).…”

A survey of extended-spectrum beta-lactamase-producing Enterobacteriaceae in urban wetlands in southwestern Nigeria as a step towards generating prevalence maps of antimicrobial resistance

“…E. coli ST617 is a member of the ST10 complex, which has emerged as important carrier mediating the spread of antimicrobial resistance genes including bla CTX-M-15 [55]. Members of the ST10 complex have a broad host range [56] and have been isolated from patients around the world including Nigeria [57,58], animals [59][60][61], food [62], and other environmental sources [48,49,63]. We are not aware of any published information on E. cloacae ST976 and C. freundii ST323 other than their mentioning in EnteroBase [64].…”

Extended Spectrum β-Lactamase (ESBL) Producing Escherichia coli in Pigs and Pork Meat in the European Union

“…The CTX-1 enzyme was discovered in 1985 from Klebsiella pneumoniae , isolated from patients in an intensive care unit in France [ 16 ]. Nowadays, it is the most widely spread β-lactamase in food-producing animals [ 17 ].…”