title: Effects of Intertidal Harvest Practices on Levels of Vibrio parahaemolyticus and Vibrio vulnificus Bacteria in Oysters.
abstract: Vibrio parahaemolyticus and Vibrio vulnificus can grow rapidly in shellfish subjected to ambient air conditions, such as during intertidal exposure. In this study, levels of total and pathogenic (tdh(+) and/or trh(+)) V. parahaemolyticus and total V. vulnificus were determined in oysters collected from two study locations where intertidal harvest practices are common. Samples were collected directly off intertidal flats, after exposure (ambient air [Washington State] or refrigerated [New Jersey]), and after reimmersion by natural tidal cycles. Samples were processed using a most-probable-number (MPN) real-time PCR method for total and pathogenic V. parahaemolyticus or V. vulnificus In Washington State, the mean levels of V. parahaemolyticus increased 1.38 log MPN/g following intertidal exposure and dropped 1.41 log MPN/g after reimmersion for 1 day, but the levels were dependent upon the container type utilized. Pathogenic V. parahaemolyticus levels followed a similar trend. However, V. vulnificus levels increased 0.10 log MPN/g during intertidal exposure in Washington but decreased by >1 log MPN/g after reimmersion. In New Jersey, initial levels of all vibrios studied were not significantly altered during the refrigerated sorting and containerizing process. However, there was an increase in levels after the first day of reimmersion by 0.79, 0.72, 0.92, and 0.71 log MPN/g for total, tdh(+) and trh(+) V. parahaemolyticus, and V. vulnificus, respectively. The levels of all targets decreased to those similar to background after a second day of reimmersion. These data indicate that the intertidal harvest and handling practices for oysters that were studied in Washington and New Jersey do not increase the risk of illness from V. parahaemolyticus or V. vulnificus
  
  
  
  Vibrio parahaemolyticus and Vibrio vulnificus are the leading causes of seafood-associated infectious morbidity and mortality in the United States. Vibrio spp. can grow rapidly in shellfish subjected to ambient air conditions, such as during periods of intertidal exposure. When oysters are submersed with the incoming tide, the vibrios can be purged. However, data on the rates of increase and purging during intertidal harvest are scarce, which limits the accuracy of risk assessments. The objective of this study was to help fill these data gaps by determining the levels of total and pathogenic (tdh(+) and/or trh(+)) V. parahaemolyticus and V. vulnificus in oysters from two locations where intertidal harvest practices are common, using the current industry practices. The data generated provide insight into the responses of Vibrio spp. to relevant practices of the industry and public health, which can be incorporated into risk management decisions.
authors.affiliation: FDA, Division of Seafood Science and Technology, Gulf Coast Seafood Laboratory, Dauphin Island, Alabama, USA Jessica.Jones@fda.hhs.gov.
authors.forename: J L
authors.initials: JL
authors.lastname: Jones
authors.affiliation: FDA, Division of Seafood Science and Technology, Gulf Coast Seafood Laboratory, Dauphin Island, Alabama, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Kinsey
authors.affiliation: Washington Department of Health, Office of Environmental Health and Safety, Tumwater, Washington, USA.
authors.forename: L W
authors.initials: LW
authors.lastname: Johnson
authors.affiliation: Washington Department of Health, Office of Environmental Health and Safety, Tumwater, Washington, USA.
authors.forename: R
authors.initials: R
authors.lastname: Porso
authors.affiliation: New Jersey Department of Environmental Protection, Bureau of Marine Water Monitoring, Leeds Point, New Jersey, USA.
authors.forename: B
authors.initials: B
authors.lastname: Friedman
authors.affiliation: New Jersey Department of Environmental Protection, Bureau of Marine Water Monitoring, Leeds Point, New Jersey, USA.
authors.forename: M
authors.initials: M
authors.lastname: Curtis
authors.affiliation: New Jersey Department of Environmental Protection, Bureau of Marine Water Monitoring, Leeds Point, New Jersey, USA.
authors.forename: P
authors.initials: P
authors.lastname: Wesighan
authors.affiliation: New Jersey Department of Environmental Protection, Bureau of Marine Water Monitoring, Leeds Point, New Jersey, USA.
authors.forename: R
authors.initials: R
authors.lastname: Schuster
authors.affiliation: FDA, Biostatistics and Bioinformatics Staff, Center for Food Safety and Applied Nutrition, College Park, Maryland, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Bowers
mesh_terms: D000818:Animals; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling; D010125:Ostreidae / Q000382:microbiology*; D012758:Shellfish / Q000382:microbiology*; D014736:Vibrio parahaemolyticus / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D041261:Vibrio vulnificus / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*