AUTHOR=Parra-Flores Julio , Holý Ondrej , Bustamante Fernanda , Lepuschitz Sarah , Pietzka Ariane , Contreras-Fernández Alejandra , Castillo Claudia , Ovalle Catalina , Alarcón-Lavín María Paula , Cruz-Córdova Ariadnna , Xicohtencatl-Cortes Juan , Mancilla-Rojano Jetsi , Troncoso Miriam , Figueroa Guillermo , Ruppitsch Werner 

TITLE=Virulence and Antibiotic Resistance Genes in Listeria monocytogenes Strains Isolated From Ready-to-Eat Foods in Chile

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.796040

DOI=10.3389/fmicb.2021.796040

ISSN=1664-302X

ABSTRACT=<p><italic>Listeria monocytogenes</italic> is causing listeriosis, a rare but severe foodborne infection. Listeriosis affects pregnant women, newborns, older adults, and immunocompromised individuals. Ready-to-eat (RTE) foods are the most common sources of transmission of the pathogen This study explored the virulence factors and antibiotic resistance in <italic>L. monocytogenes</italic> strains isolated from ready-to-eat (RTE) foods through <italic>in vitro</italic> and <italic>in silico</italic> testing by whole-genome sequencing (WGS). The overall positivity of <italic>L. monocytogenes</italic> in RTE food samples was 3.1% and 14 strains were isolated. <italic>L. monocytogenes</italic> ST8, ST2763, ST1, ST3, ST5, ST7, ST9, ST14, ST193, and ST451 sequence types were identified by average nucleotide identity, ribosomal multilocus sequence typing (rMLST), and core genome MLST. Seven isolates had serotype 1/2a, five 1/2b, one 4b, and one 1/2c. Three strains exhibited <italic>in vitro</italic> resistance to ampicillin and 100% of the strains carried the <italic>fosX</italic>, <italic>lin</italic>, <italic>norB</italic>, <italic>mprF</italic>, <italic>tetA</italic>, and <italic>tetC</italic> resistance genes. In addition, the <italic>arsBC</italic>, <italic>bcrBC</italic>, and <italic>clpL</italic> genes were detected, which conferred resistance to stress and disinfectants. All strains harbored <italic>hlyA</italic>, <italic>prfA</italic>, and <italic>inlA</italic> genes almost thirty-two the showed the <italic>bsh, clpCEP, hly, hpt, iap/cwhA, inlA, inlB, ipeA, lspA, mpl, plcA, pclB, oat, pdgA</italic>, and <italic>prfA</italic> genes. One isolate exhibited a type 11 premature stop codon (PMSC) in the <italic>inlA</italic> gene and another isolate a new mutation (deletion of A in position 819). The Inc18(rep25), Inc18(rep26), and N1011A plasmids and MGEs were found in nine isolates. Ten isolates showed CAS-Type II-B systems; in addition, Anti-CRISPR AcrIIA1 and AcrIIA3 phage-associated systems were detected in three genomes. These virulence and antibiotic resistance traits in the strains isolated in the RTE foods indicate a potential public health risk for consumers.</p>