Genomic Characterization of Antimicrobial Resistance in Food Chain and Livestock-Associated <i>Salmonella</i> Species

• Main Authors: Thobeka P. Mthembu, Oliver T. Zishiri, Mohamed E. El Zowalaty
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Animals
• Subjects: antimicrobial resistance; <i>Enterobacteriacae</i>; <i>Salmonella</i>; foodborne; food chain; livestock zoonosis
• Online Access: https://www.mdpi.com/2076-2615/11/3/872

The rising trend of antimicrobial resistance (AMR) by foodborne bacteria is a public health concern as these pathogens are easily transmitted to humans through the food chain. Non-typhoid <i>Salmonella</i> spp. is one of the leading foodborne pathogens which infect humans worldwide and is associated with food and livestock. Due to the lack of discovery of new antibiotics and the pressure exerted by antimicrobial resistance in the pharmaceutical industry, this review aimed to address the issue of antibiotic use in livestock which leads to AMR of <i>Salmonella</i>. Much attention was given to resistance to carbapenems and colistin which are the last-line antibiotics used in cases of multi drug resistant bacterial infections. In the present review, we highlighted data published on antimicrobial resistant <i>Salmonella</i> species and serovars associated with livestock and food chain animals. The importance of genomic characterization of carbapenem and colistin resistant <i>Salmonella</i> in determining the relationship between human clinical isolates and food animal isolates was also discussed in this review. Plasmids, transposons, and insertion sequence elements mediate dissemination of not only AMR genes but also genes for resistance to heavy metals and disinfectants, thus limiting the therapeutic options for treatment and control of <i>Salmonella</i>. Genes for resistance to colistin (<i>mcr-1</i> to <i>mcr-9</i>) and carbapenem (<i>blaVIM-1</i>, <i>blaDNM-1</i>, and <i>blaNDM-5</i>) have been detected from poultry, pig, and human <i>Salmonella</i> isolates, indicating food animal-associated AMR which is a threat to human public health. Genotyping, plasmid characterization, and phylogenetic analysis is important in understanding the epidemiology of livestock-related <i>Salmonella</i> so that measures of preventing foodborne threats to humans can be improved.