Occurrence of Mobile Colistin Resistance Genes mcr-1–mcr-10 including Novel mcr Gene Variants in Different Pathotypes of Porcine Escherichia coli Isolates Collected in Germany from 2000 to 2021

Abstract

In the European Union, gastrointestinal disease in pigs is the main indication for the use of colistin, but large-scale epidemiologic data concerning the frequency of mobile colistin resistance (mcr) genes in pig-associated pathotypes of Escherichia coli (E. coli) are lacking. Multiplex polymerase chain reactions were used to detect virulence-associated genes (VAGs) and mcr-1–mcr-10 genes in 10,573 porcine E. coli isolates collected in Germany from July 2000 to December 2021. Whole genome sequencing was performed on 220 representative mcr-positive E. coli strains. The total frequency of mcr genes was 10.2%, the most frequent being mcr-1 (8.4%) and mcr-4 (1.6%). All other mcr genes were rarely identified (mcr-2, mcr-3, mcr-5) or absent (mcr-6 to mcr-10). The highest frequencies of mcr genes were found in enterotoxigenic and shiga toxin-encoding E. coli (ETEC/STEC hybrid) and in edema disease E. coli (EDEC) strains (21.9% and 17.7%, respectively). We report three novel mcr variants, mcr-1.36, mcr-4.8, and mcr-5.5. In 39 attaching and effacing E. coli (AEEC) isolates analyzed in our study, the eae subtype β1 was the most prevalent (71.8%). Constant surveillance for the presence of mcr genes in various sectors should consider the different frequency of mcr-positive isolates in pathogenic E. coli.

First detection and characterization of mcr-1 colistin resistant E. coli from wild rat in Bangladesh

“…coli strain ATCC25922 was used as the positive and negative controls, respectively. On the other hand uniplex PCR was performed for the detection of mcr-6 to mcr-10 following the in-house protocol developed by Awasthi et al [Unpublished] and Göpel et al, 2023 [ 23 ].…”

Repeated Occurrence of Mobile Colistin Resistance Gene-Carrying Plasmids in Pathogenic Escherichia coli from German Pig Farms

“…From our database of more than 3000 registered pig farms in Germany that had sent samples for molecular typing of E. coli isolates in the past, we selected only farms from which at least 25 pathogenic E. coli isolates had been obtained and preserved over the years (n = 23 farms). This was based on our recently published collection of 10,573 E. coli isolates, each harboring at least one of ten VAGs, which were tested using PCR for the presence of mcr-1 to mcr-10 genes [30]. Briefly, E. coli isolates were obtained from feces or mucosal swabs (rectum or small intestine).…”

“…After approximately 18 h of incubation at 37 • C, up to six morphologically different, putative E. coli colonies were picked per sample and tested for the presence of VAGs. More details of sample collection and processing were published recently [30].…”

“…Samples were obtained from 43 pigs, most of them suffering from diarrheal disease. From this sample material, 50 E. coli isolates were cultivated that were positive for at least one VAG associated with certain pathotypes of InPEC as determined by PCR [30]. Twenty-two (44%) of these E. coli isolates, obtained from July 2009 to September 2012, tested positive for mcr-1 genes (Table 1).…”

“…A prediction of pathotypes was conducted for all 154 E. coli isolates included in this study based on the presence of certain VAGs obtained from PCR analysis, as described previously [30]: adhesive fimbriae E. coli (in the following termed AdhF-Ec), positive only for at least one adhesive fimbriae gene (faeG, fanA, fasA, fedA and fimF41a); AEEC (often also referred to as atypical EPEC), positive for eae; EDEC, positive for fedA and stx2; ETEC, positive for at least one adhesive fimbriae gene (faeG, fanA, fasA, fedA and fimF41a) and at least one enterotoxin gene (eltB-Ip, estap and estb); ETEC-like, positive only for at least one enterotoxin gene (eltB-Ip, estap and estb); ETEC/STEC hybrid (in the following simply termed ETEC/STEC), positive for at least one adhesive fimbriae gene (faeG, fanA, fasA, fedA and fimF41a) and at least one enterotoxin gene (eltB-Ip, estap and estb) and stx2; STEC, positive only for stx2.…”