Location: Produce Safety and Microbiology Research
Title: Plasmidome of Salmonella enterica serovar Infantis recovered from surface waters in a major agricultural region for leafy greens in CaliforniaAuthor
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Quinones, Beatriz |
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Lee, Bertram |
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Aviles Noriega, Ashley |
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Gorski, Lisa |
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/11/2024 Publication Date: 12/30/2024 Citation: Quinones, B., Lee, B.G., Aviles Noriega, A., Gorski, L.A. 2024. Plasmidome of Salmonella enterica serovar Infantis recovered from surface waters in a major agricultural region for leafy greens in California. PLOS ONE. 19(12). Article e0316466. https://doi.org/10.1371/journal.pone.0316466. DOI: https://doi.org/10.1371/journal.pone.0316466 Interpretive Summary: The bacterial pathogen Salmonella enterica is a leading cause of gastrointestinal illness with mild to moderate clinical manifestations in humans. Approximately 2,600 different serovars have been identified in S. enterica, and only 100 serovars are significantly responsible for human illness. In particular, S. enterica serovar Infantis has now been ranked as the sixth most common serovar associated with foodborne disease in the United States. In the present study, high-resolution sequencing was employed to identify virulence and antimicrobial resistance determinants in mobilizable plasmids detected in S. enterica serovar Infantis strains, recovered from surface waters adjacent to leafy greens farms in California. Technical Abstract: Non-typhoidal Salmonella enterica is a leading cause of gastrointestinal illnesses in the United States. Among the 2,600 different S. enterica serovars, Infantis has been significantly linked to human illnesses and is frequently recovered from broilers and chicken parts in the U.S. A key virulence determinant in serovar Infantis is the presence of the megaplasmid pESI, conferring multidrug resistance. To further characterize the virulence potential of this serovar, the present study identified the types of plasmids harbored by Infantis strains, recovered from surface waters adjacent to leafy greens farms in California. Sequencing analysis showed that each of the examined 12 Infantis strains had a large plasmid ranging in size from 78 kb to 125 kb. In addition, a second 4-kb plasmid was detected in two strains. Plasmid nucleotide queries did not identify the emerging megaplasmid pESI in the examined Infantis strains; however, the detected plasmids had similarity to a plasmid sequence already cataloged in the nucleotide databases. Subsequent comparative analyses, based on gene presence or absence, divided the detected the plasmids into five distinct clusters, and the phylogram revealed these Infantis plasmids were clustered based either on the plasmid conjugation system, Inc1 and IncF, or on the presence of plasmid phage genes. Assignment of the putative genes to functional categories revealed that the large plasmids contained genes implicated in cell cycle control and division, replication and recombination and defense mechanisms. Further analysis of the mobilome, including prophages and transposons, demonstrated the presence of genes implicated in the release of the bactericidal peptide microcin in the IncF plasmids and identified a Tn10 transposon conferring tetracycline resistance in one of the Inc1 plasmids. These findings indicated that the plasmids in the environmental Infantis strains from surface waters harbored a wide variety of genes associated with adaptation, survivability and antimicrobial resistance. |