Genetic Carriers and Genomic Distribution of -A Novel Variant of a Cadmium Resistance Determinant Identified in spp.

is a pathogen responsible for severe cases of food poisoning. spp. strains occurring in soil and water environments may serve as a reservoir of resistance determinants for pathogenic strains. A large collection of spp. strains (155) isolated from natural, agricultural, and urban areas was screened for resistance to heavy metals and metalloids, and the presence of resistance determinants and extrachromosomal replicons. Of the tested strains, 35% were resistant to cadmium and 17% to arsenic. Sequence analysis of resistance plasmids isolated from strains of and , and the chromosome of strain Sr73, identified a novel variant of the cadmium resistance efflux system, , that was functional in cells. The cassette was detected in four species, including strains of , isolated from various countries and sources-environmental, food-associated, and clinical samples. This resistance cassette is harbored by four novel composite or non-composite transposons, which increases its potential for horizontal transmission. Since some cassettes may influence virulence and biofilm formation, it is important to monitor their presence in spp. strains inhabiting different environments.