Browsing by Author "Brown, Phillip"

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    Draft Genome Sequences of 158 Listeria monocytogenes Strains Isolated from Black Bears (Ursus americanus) in the United States
    Brown, Phillip; Chen, Yi; Ivanova, Mirena; Leekitcharoenphon, Pimlapas; Parsons, Cameron; Niedermeyer, Jeffrey; Gould, Nicholas; Strules, Jennifer; Mesa-Cruz, J. Bernardo; Kelly, Marcella J.; Hooker, Michael J.; Chamberlain, Michael J.; Olfenbuttel, Colleen; DePerno, Christopher; Elhanafi, Driss; Kathariou, Sophia (American Society for Microbiology, 2023-06)
    Listeria monocytogenes is responsible for severe foodborne disease and major economic losses, but its potential reservoirs in natural ecosystems remain poorly understood. Here, we report the draft genome sequences of 158 L. monocytogenes strains isolated from black bears (Ursus americanus) in the southeastern United States between 2014 and 2017. Listeria monocytogenes is responsible for severe foodborne disease and major economic losses, but its potential reservoirs in natural ecosystems remain poorly understood. Here, we report the draft genome sequences of 158 L. monocytogenes strains isolated from black bears (Ursus americanus) in the southeastern United States between 2014 and 2017.
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    Harnessing Whole Genome Sequence Data for Facility-Specific Signatures for Listeria monocytogenes: A Case Study With Turkey Processing Plants in the United States
    Brown, Phillip; Chen, Yi; Siletzky, Robin; Parsons, Cameron; Jaykus, Lee-Ann; Eifert, Joseph D.; Ryser, Elliot; Logue, Catherine M.; Stam, Christina; Brown, Eric; Kathariou, Sophia (2021-10-13)
    Listeria monocytogenes is a Gram-positive foodborne pathogen responsible for the severe disease listeriosis and notorious for its ability to persist in food processing plants, leading to contamination of processed, ready-to-eat foods. L. monocytogenes persistence in various food processing environments (FPEs) has been extensively investigated by various subtyping tools, with increasing use of whole genome sequencing (WGS). However, major knowledge gaps remain. There is a need for facility-specific molecular signatures not only for adequate attribution of L. monocytogenes to a specific FPE but also for improved understanding of the ecology and evolution of L. monocytogenes in the food processing ecosystem. Furthermore, multiple strains can be recovered from a single FPE sample, but their diversity can be underestimated with common molecular subtyping tools. In this study we investigated a panel of 54 L. monocytogenes strains from four turkey processing plants in the United States. A combination of WGS and phenotypic assays was employed to assess strain persistence as well as identify facility-specific molecular signatures. Comparative analysis of allelic variation across the whole genome revealed that allelic profiles have the potential to be specific to individual processing plants. Certain allelic profiles remained associated with individual plants even when closely-related strains from other sources were included in the analysis. Furthermore, for certain sequence types (STs) based on the seven-locus multilocus sequence typing scheme, presence and location of premature stop codons in inlA, inlB length, prophage sequences, and the sequence content of a genomic hotspot could serve as plant-specific signatures. Interestingly, the analysis of different isolates from the same environmental sample revealed major differences not only in serotype and ST, but even in the sequence content of strains of the same ST. This study highlights the potential for WGS data to be deployed for identification of facility-specific signatures, thus facilitating the tracking of strain movement through the food chain. Furthermore, deployment of WGS for intra-sample strain analysis allows for a more complete environmental surveillance of L. monocytogenes in food processing facilities, reducing the risk of failing to detect strains that may be clinically relevant and potentially novel.
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    Listeria monocytogenes at the human-wildlife interface: black bears (Ursus americanus) as potential vehicles for Listeria
    Parsons, Cameron; Niedermeyer, Jeff; Gould, Nicholas; Brown, Phillip; Strules, Jennifer; Parsons, Arielle W.; Mesa-Cruz, J. Bernardo; Kelly, Marcella J.; Hooker, Michael J.; Chamberlain, Michael J.; Olfenbuttel, Colleen; DePerno, Christopher; Kathariou, Sophia (2019-11)
    Listeria monocytogenes is the causative agent of the foodborne illness listeriosis, which can result in severe symptoms and death in susceptible humans and other animals. L. monocytogenes is ubiquitous in the environment and isolates from food and food processing, and clinical sources have been extensively characterized. However, limited information is available on L. monocytogenes from wildlife, especially from urban or suburban settings. As urban and suburban areas are expanding worldwide, humans are increasingly encroaching into wildlife habitats, enhancing the frequency of human-wildlife contacts and associated pathogen transfer events. We investigated the prevalence and characteristics of L. monocytogenes in 231 wild black bear capture events between 2014 and 2017 in urban and suburban sites in North Carolina, Georgia, Virginia and United States, with samples derived from 183 different bears. Of the 231 captures, 105 (45%) yielded L. monocytogenes either alone or together with other Listeria. Analysis of 501 samples, primarily faeces, rectal and nasal swabs for Listeria spp., yielded 777 isolates, of which 537 (70%) were L. monocytogenes. Most L. monocytogenes isolates exhibited serotypes commonly associated with human disease: serotype 1/2a or 3a (57%), followed by the serotype 4b complex (33%). Interestingly, approximately 50% of the serotype 4b isolates had the IVb-v1 profile, associated with emerging clones of L. monocytogenes. Thus, black bears may serve as novel vehicles for L. monocytogenes, including potentially emerging clones. Our results have significant public health implications as they suggest that the ursine host may preferentially select for L. monocytogenes of clinically relevant lineages over the diverse listerial populations in the environment. These findings also help to elucidate the ecology of L. monocytogenes and highlight the public health significance of the human-wildlife interface.