AUTHOR=Hu Lijun , Brown Eric W. , Zhang Guodong 

TITLE=Diversity of antimicrobial resistance, stress resistance, and virulence factors of Salmonella, Shiga toxin-producing Escherichia coli, and Listeria monocytogenes from produce, spices, and tree nuts by whole genome sequencing

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=7

YEAR=2023

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2023.1281005

DOI=10.3389/fsufs.2023.1281005

ISSN=2571-581X

ABSTRACT=<sec><title>Introduction</title><p>The objective of this study was to analyze antimicrobial resistance (AMR), stress resistance, and virulence factors through whole genome sequencing (WGS) of 192 isolates comprising 164 <italic>Salmonella</italic> isolates, 8 non-O157 Shiga toxin-producing <italic>Escherichia coli</italic> (STEC) isolates, and 20 <italic>Listeria monocytogenes</italic> isolates.</p></sec><sec><title>Methods</title><p>These isolates were sourced from a national survey conducted between 2010 and 2017, involving 31,322 samples of produce (31 isolates), nuts (43 isolates), and spices (118 isolates).</p></sec><sec><title>Results</title><p>The findings yielded several key insights: (1) Within all <italic>Salmonella</italic> isolates studied, the most prevalent <italic>Salmonella</italic> serotypes included Give, Kentucky, Senftenberg, Mbandaka, Anatum, Newport, and Weltevreden. (2) All eight non-O157 STEC isolates were found to carry the genes <italic>blaEC</italic>, <italic>acrF</italic>, and <italic>mdtM</italic>, while all 20 <italic>L. monocytogenes</italic> isolates possessed <italic>fosX</italic> and <italic>lin</italic> genes. The <italic>Salmonella</italic> isolates displayed diverse AMR gene profiles, with 3.65% exhibiting multi-drug resistance. (3) Both <italic>Salmonella</italic> and non-O157 STEC isolates were discovered to carry stress genes associated with acid resistance, but none of the <italic>L. monocytogenes</italic> isolates carried an acid resistance gene. <italic>Salmonella</italic> isolates were found to carry multiple metal-resistance genes. The non-O157 STEC isolates universally exhibited acid resistance genes, and 4 out of the 20 <italic>L. monocytogenes</italic> isolates were equipped with resistance genes against biocides. (4) All of the STEC isolates (100%) carried <italic>stx1</italic> and <italic>stx2</italic> genes, while none of them carried <italic>eae</italic> and <italic>wyz</italic> genes. Most <italic>L. monocytogenes</italic> isolates were found to contain 29 virulence genes and 1 pathogenicity island. All <italic>Salmonella</italic> isolates carried SPI-9, but lacked SPI-7, SPI-10, SPI-11, SPI-12, mig-5, <italic>prefA</italic>, <italic>tviA</italic>, and <italic>viaB</italic> genes.</p></sec><sec><title>Conclusion</title><p>These findings on AMR, stress resistance, and virulence factors among the investigated isolates highlight the potential risks they pose to public health and provide the scientific foundation for the development of preventative and control strategies and guidance pertaining to these major foodborne pathogens.</p></sec>