Author
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Ravva, Subbarao |
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Sarreal, Chester |
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Mandrell, Robert |
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Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/18/2014 Publication Date: 7/14/2014 Citation: Ravva, S.V., Sarreal, C.Z., Mandrell, R.E. 2014. Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. PLoS One. 9(7):e102412. doi:10.1371/journal.pone.0102412. Interpretive Summary: Pre-harvest contamination of produce is known to be associated with some foodborne illness outbreaks. In order to understand how this contamination occurs, it is important to know how pathogens survive in the environment, croplands, dairies and feedlots. It is known that pathogens persist under harsh environmental conditions. In this work, we compared the fate of E. coli pathogens from 2006 baby spinach outbreak for survival in dry field soil and predation by protozoa isolated from dairy wastewater. We found pathogens previously exposed to harsh environments survive longer and resist predation and may be the ones that may contaminate and proliferate on produce crops. Technical Abstract: Escherichia coli O157:H7 (EcO157) associated with 2006 spinach outbreak appears to have persisted as the organism was later isolated from environmental samples in the produce production areas of central coast of California. Survival in harsh environments was often linked to the inherent fitness characteristics of EcO157. This study evaluated the comparative fitness of outbreak-related clinical and environmental strains to resist protozoan predation and survive in soil from a spinach field in the general vicinity of isolation of strains genetically indistinguishable from the outbreak strain. Environmental strains from soil and pig feces survived longer (11 to 35 days for 90% decreases, D-value) with Vorticella microstoma and Colpoda aspera, previously isolated from dairy |
