ARS | Publication request: Genetic determinants for cadmium and arsenic resistance among Listeria monocytogenes serotype 4b isolates from sporadic human listeriosis patients

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2013
Publication Date: February 1, 2013
Citation: Lee, S., Rakic-Martinez, M., Graves, L.M., Ward, T.J., Siletzky, R.M., Kathariou, S. 2013. Genetic determinants for cadmium and arsenic resistance among Listeria monocytogenes serotype 4b isolates from sporadic human listeriosis patients. Applied and Environmental Microbiology. 79(7):2471-2476.

Interpretive Summary: Listeria monocytogenes is a food-borne bacterium that places a serious burden on human health and the agricultural economy. However, not all L. monocytogenes strains are equally likely to persist in food environments. In this study, we characterized the genes for heavy metal resistance among a panel of L. monocytogenes from foods and processing plant environments. We identified an unexpected connection between heavy metal resistance genes and particular groups of L. monocytogenes strains responsible for sporadic human listeriosis infections. We also describe novel genetic factors contributing to heavy metal resistance and our findings indicate that strains associated with human listeriosis in the United States possess a complex array of heavy metal resistance genes. These data provide new information about the genes used by L. monocytogenes to persist in different environments and will be of direct interest to epidemiologists, public health and food inspection agencies, and scientists involved in food safety research.

Technical Abstract: In Listeria monocytogenes serotype 4b from sporadic listeriosis, heavy metal resistance was primarily encountered in certain clonal groups (ECI, ECII, ECIa). All arsenic-resistant isolates harbored the arsenic resistance cassette previously identified in pLI100; ECIa harbored additional arsenic resistance genes and a novel cadmium resistance determinant in a conserved chromosomal locus.