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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR & BIOCHEMICAL DETECTION & INTERVENTION METHODS FOR BACTERIAL AND VIRAL PATHOGENS IN AQUACULTURE PRODUCTS

Location: Food Safety and Intervention Technologies

Title: Shewanella and Photobacterium in Oysters and Seawater from the Delaware Bay

Authors
item Richards, Gary
item Watson, Michael
item Crane, Edward - POMONA COLLEGE
item Bushek, David - HASKIN SHELLFISH RES.LAB
item Burt, Iris - HASKIN SHELLFISH RES.LAB

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2008
Publication Date: June 1, 2008
Citation: Richards, G.P., Watson, M.A., Crane, E.J., Bushek, D., Burt, I. 2008. Shewanella and photobacterium in oysters and seawater from the delaware bay. Applied and Environmental Microbiology. 74(11):3323-3327.

Interpretive Summary: As part of a two-year study of the bacterial flora of commercial oyster harvesting sites in the Delaware Bay, we identified Shewanella species in oysters and seawater. Shewanella are bacteria that are typically found in the marine environment and two species are known to cause disease in man. Shewanella algae and Shewanella putrefaciens cause blood- and tissue-associated infections including septicemia; soft tissue, bone, and ear infections; arthritis; abscesses; and death. We report, for the first time, the detection of S. algae, S. putrefaciens, and four other Shewanella species in oysters and seawater from the Delaware Bay. Recent reports link Shewanella illnesses with the consumption of raw fish, so their detection in the Delaware Bay signals another group of bacteria that may be transmitted through shellfish and other seafoods. Another potential disease-causing bacterium, Photobacterium damselae, was also identified at lower levels. In addition to seafood consumption, cuts and abrasions, swimming, and other recreational activities in the marine environment may increase the risk for Shewanella and Photobacterium infections. This study demonstrated the need for improved detection methods and for enhanced monitoring of Shewanella and Photobacterium levels in the Delaware Bay.

Technical Abstract: Shewanella algae, S. putrefaciens, and Photobacterium damselae subsp. damselae are indigenous marine bacteria and human pathogens causing cellulitis, necrotizing fasciitis, abscesses, septicemia, and death. Infections are rare and are most often associated with the immunocompromized host. A study was performed on the microbiological flora of oysters and seawater from commercial harvesting sites in the Delaware Bay, New Jersey. From 276 samples tested, 1,421 bacterial isolates were picked for biochemical identification and 170 (12.0%) of the isolates were presumptively identified as S. putrefaciens, 26 (1.8%) were presumptively identified as P. damselae subsp. damselae, and 665 (46.8%) could not be identified using the API 20E identification database. Sequencing of the 16S rRNA gene of 22 S. putrefaciens-like isolates identified them as S. abalonesis, S. algae, S. baltica, S. hafniensis, S. marisflavi, S. putrefaciens, Listonella anguillarum, and P. damselae. Beta-hemolysis was produced by S. algae and P. damselae, while S. baltica and L. anguillarum, species perceived as non-pathogenic, also exhibited beta-hemolysis and growth at 37 degree C. To our knowledge, this is the first time beta-hemolytic strains were reported in shellfish or seawater from the Delaware Bay. Pathogenic Shewanella and Photobacterium species could pose a health threat through the ingestion of contaminated seafoods, by cuts or abrasions acquired in the marine environment, or by swimming and other recreational activities. Improved methods for their detection are needed.

Last Modified: 8/1/2014
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