Characterization of ESBL-producing Escherichia spp. and report of an mcr-1 colistin-resistance Escherichia fergusonni strain from minced meat in Pamplona, Colombia.

Foods of animal origin are increasingly considered a source of extended spectrum β-lactamase (ESBL) producing bacteria which can disseminate throughout the food chain and become a health concern for humans. This work aimed to evaluate the occurrence of ESBL-producing Escherichia coli in 100 retail minced meat samples taken in markets in Pamplona, Colombia. A total of 19 ESBL-producing isolates were obtained, 18 identified as E. coli and one as E. fergusonii. Fifteen isolates (78.9 %) carried bla _CTX-M and bla _TEM genes, one (5.2 %) bla _SHV and bla _TEM genes, one isolate (5.2 %) carried bla _CTX-M and one (5.2 %) bla _SHV alone. The majority of CTX-M-positive E. coli isolates carried the bla _CTX-M-15 gene (13 isolates), being the bla _CTX-M-9 , bla _CTX-M-2 , and bla _CTX-M-8 (one isolate each) also detected. Two SHV-positive isolates presented the bla _SHV-5 and bla _SHV-12 allele. The isolate identified as E. fergusonii was positive for bla _CTX-M-65 gene and mcr-1 gene. Sixteen isolates (84.2 %) belonged to phylogroups A and B1 and grouped together in the phylogenetic tree obtained by MLST; phylogroups E and F were also detected. Transfer of ESBL resistance was demonstrated for the E. fergusonii isolate. Whole genome sequencing of this isolate revealed the presence of plasmids carrying additional resistance genes. This investigation showed the high prevalence of ESBL-producing E. coli in retail samples of minced meat. Also, the isolation of a strain of E. fergusonii is an additional concern, as some resistance genes are located in mobile elements, which can be transmitted to other bacteria. These evidences support the increasing public health concern considering the spreading of resistance genes through the food chain.
Competing Interests: Declaration of competing interest There are no conflicts of interest among authors.
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