Salmonella newport contamination of produce: Ecological, genetic and epidemiological aspects

Rebecca L. Bell, Guojie Cao, Jianghong Meng, Marc W. Allard, Christine Keys, Thomas Hill, Andrea Ottesen, Eric Wayne Brown

Research output: Chapter in Book/Report/Conference proceedingChapter

3 Scopus citations

Abstract

Salmonella enterica is the most frequent source of bacterial foodborne illness in the U.S., causing an estimated 1.4 million cases of salmonellosis annually. Historically, infection by Salmonella occurs after eating undercooked meats, poultry and eggs. However, over the past decade, the consumption of raw ready-to-eat produce has been implicated in several severe and widespread outbreaks within the U. S. Most notably, an S. enterica Saintpaul outbreak associated with jalapeňo and Serrano peppers sickened over 1400 individuals during the summer of 2008. One Salmonella serovar in particular, Salmonella enterica Newport, has been associated perennially with contamination events involving fresh tomatoes and prepared fresh foods containing tomatoes. S. Newport is a non-typhoidal salmonellae classified taxonomically as subspecies (i.e. "group") I Salmonella enterica enterica. Prior to its emergence in produce and in produce growing environments, S. Newport was found predominantly in swine, cattle and other livestock commodities. S. Newport association with tomatoes retains a geographically skewed distribution. Metagenomic analyses of tomato phyllopsheres, based on 16S rDNA sequences and deep genome sequencing of tomato microbial communities, point to resident colonization on tomatoes from the Mid-Atlantic growing regions but not other predominant fresh tomato growing regions such as Florida or California, signaling niche adaptation of S. Newport in some growing environments but not others. Genetic analysis of S. Newport has revealed specific differences among strains from disparate locales. Pulsed-field gel electrophoresis, for example, has yielded several pulsotypes of environmental S. Newport primarily associated with the Virginia eastern shore, a prominent fresh tomato production region of the county. Whole-genome sequencing affirmed these phylo-geographic differences within the serovar. Surprisingly, certain genotypes of S. Newport have been isolated from this region that genetically match previous outbreaks where tomatoes were a suspected vehicle. S. Newport can be readily detected in the environment of the Virginian eastern shore growing region using both molecular (i.e. PCR) and microbiological (i.e. FDA-BAM) screening methods. Taken together, these issues highlight the important intersection of microbiological, genetic, and ecological investigation for fully understanding the complex life cycle of this dangerous foodborne pathogen.

Original languageEnglish (US)
Title of host publicationSalmonella
Subtitle of host publicationClassification, Genetics and Disease Outbreaks
PublisherNova Science Publishers, Inc.
Pages155-174
Number of pages20
ISBN (Print)9781619429284
StatePublished - Dec 1 2012

All Science Journal Classification (ASJC) codes

  • Medicine(all)

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    Bell, R. L., Cao, G., Meng, J., Allard, M. W., Keys, C., Hill, T., Ottesen, A., & Brown, E. W. (2012). Salmonella newport contamination of produce: Ecological, genetic and epidemiological aspects. In Salmonella: Classification, Genetics and Disease Outbreaks (pp. 155-174). Nova Science Publishers, Inc..