CTX-M-15-Producing E. coli Isolates from Food Products in Germany Are Mainly Associated with an IncF-Type Plasmid and Belong to Two Predominant Clonal E. coli Lineages

Abstract

Extended-spectrum beta-lactamases (ESBL) mediating resistance to 3rd generation cephalosporins are a major public health issue. As food may be a vehicle in the spread of ESLB-producing bacteria, a study on the occurrence of cephalosporin-resistantu Escherichia coli in food was initiated. A total of 404 ESBL-producing isolates were obtained from animal-derived food samples (e.g., poultry products, pork, beef and raw milk) between 2011 and 2013. As CTX-M-15 is the most abundant enzyme in ESBL-producing E. coli causing human infections, this study focusses on E. coli isolates from food samples harboring the blaCTX-M-15 gene. The blaCTX-M-15 gene was detected in 5.2% (n = 21) of all isolates. Molecular analyses revealed a phylogenetic group A ST167 clone that was repeatedly isolated from raw milk and beef samples over a period of 6 months. The analyses indicate that spread of CTX-M-15-producing E. coli in German food samples were associated with a multireplicon IncF (FIA FIB FII) plasmid and additional antimicrobial resistance genes such as aac(6)-Ib-cr, blaOXA−1, catB3, different tet-variants as well as a class 1 integron with an aadA5/dfrA17 gene cassette. In addition, four phylogenetic group A ST410 isolates were detected. Three of them carried a chromosomal copy of the blaCTX-M-15 gene and a single isolate with the gene on a 90 kb IncF plasmid. The blaCTX-M-15 gene was always associated with the ISEcp1 element. In conclusion, CTX-M-15-producing E. coli were detected in German food samples. Among isolates of different matrices, two prominent clonal lineages, namely A-ST167 and A-ST410, were identified. These lineages may be important for the foodborne dissemination of CTX-M-15-producing E. coli in Germany. Interestingly, these clonal lineages were reported to be widely distributed and especially prevalent in isolates from humans and livestock. Transmission of CTX-M-15-harboring isolates from food-producing animals to food appears probable, as isolates obtained from livestock and food samples within the same time period exhibit comparable characteristics as compared to isolates detected from human. However, the routes and direction of transmission need further investigation.

MinION nanopore sequencing identifies the position and structure of bacterial antibiotic resistance determinants in a multidrug-resistant strain of enteroaggregative Escherichia coli

“…The AMR determinants located on this integron were catA , bla OXA-1 , aac(6′)-Ib- cr, tetA and bla CTX-M-15 , conferring reduced susceptibility to chloramphenicol, ampicillin, streptomycin and ciprofloxacin, tetracycline and the third-generation cephalosporins. bla CTX-M-15 is the most abundant CTX-M gene in ESBL (extended-spectrum beta-lactamase)-producing E. coli causing human infections [ 8 ]. Analysis using blast n indicated that the AMR determinants on this transposon originated from two different fragments of DNA originating from different plasmids (Accessions: NC_014384.1 and MF353155.1) inserted into a fragment of DNA that originated from a strain of Enterobacter cloace ( Fig.…”

Spread of bla CTX-M-15 -Producing Enterobacteriaceae and OXA-23-Producing Acinetobacter baumannii Sequence Type 2 in Tunisian Seafood

“…Surprisingly, hybridizations on S1-PFGE gels revealed a unique bla CTX-M-15bearing IncF plasmid of the F31:A4:B1 formula in all ST617 and ST410 isolates and in one ST131 isolate. This very same bla CTX-M-15 IncF plasmid has regularly been identified in ST617 and ST410 in numerous animal species, foodstuffs, and countries worldwide (12)(13)(14)(15)(16), and in two ST44 and ST131 clinical isolates in the United States (17), thereby suggesting that this plasmid is a major genetic support for the dissemination of bla CTX-M-15 .…”

Prevalence of extended-spectrum β-lactamases in the local farm environment and livestock: challenges to mitigate antimicrobial resistance

“…Moreover, Nesme et al (2014) found ARGs from different environments (soil, ocean, and human faeces), and showed soil and human faeces shared ARGs (24/94), suggesting that genes flow between these environments (Nesme et al 2014). Also, several MGEs such as conjugative plasmids including incompatibility groups (Inc) F, A/C, N, HI2, I1, and K with specific insertion sequences (IS) such as ISEcp1 and ISCR1 elements are frequently reported with ESBLs (Ali et al 2016;Irrgang et al 2017Irrgang et al , 2018, indicating these IS elements are strongly associated with independent acquisition of the ESBL genes. IncN plasmids encoding CTX-M-1 have been found in bacteria isolated from pigs, farmers, and farm environments, such as manure and air, indicating the spread of conjugative IncN plasmids with bla CTX-M genes among pigs, farmers, and surroundings (Moodley and Guardabassi 2009).…”