Occurrence of genetic determinants of plasmid-mediated colistin resistance in gram-negative bacteria in foodstuffs and the natural environment of the Czech Republic

The use of antimicrobials in agricultural production including the treatment of infectious animal diseases caused by bacterial agents is considered to be one of the most significant risks of development and spread of resistance in bacteria. The present study focused on the determination of the occurrence of genetic determinants of plasmid-mediated colistin resistance in poultry meat and fishery products from the retail market and the natural environment of the Czech Republic (CR). With the exception of the mcr-2 and mcr-6 genes, all of the mcr-1 to mcr-8 genes of interest were detected in the tested samples. Significant sources of mcr genes were mainly samples of turkey meat originating from EU countries and fishery products mainly imported from Asia. E. coli with mcr-1 gene was the dominant one. In Enterobacteriaceae isolates with the mcr-1 gene, were the most frequently detected plasmid was IncX4. The occurrence of gram-negative bacteria carrying different variants of the mcr gene in fishery products points to the importance of the aquatic environment in the spread of plasmid-mediated colistin resistance. This is confirmed by the spread of the mobile colistin resistance genes in surface waters. After isolation of total DNA, all samples from wastewater treatment plants were positive for the presence of some of the mcr genes, which may predict the previously unspecified spread of plasmid-mediated colistin resistance also in the human population of the Czech Republic. ; CZ; pdf; efsa.focalpoint@mze.cz