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Chapter 5 : Shellfish and Microbial Source Tracking
Category: Environmental Microbiology; Applied and Industrial Microbiology
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This chapter reviews the impact of fecal contamination on the shellfish industry, summarizes the legal framework for regulation of the sanitary quality of shellfish, and examines the use of microbial source tracking (MST) techniques as applied to shellfish growing waters. Broadly, the microbial contaminants associated with shellfish-borne disease may be classified as either (i) being naturally occurring (autochthonous) in shellfish-growing waters or (ii) related to fecal contamination of the growing waters (allochthonous). Under the National Shellfish Sanitation Program (NSSP), shellfish-growing waters are classified as approved, conditionally approved, conditionally restricted, restricted, or prohibited. Several methods of MST have been described for identification of fecal pollution sources in contaminated water. These methods may be divided broadly into two distinct classes, library-dependent and libraryless methods. The techniques may be further classified as based on phenotypic or genotypic characterization of microbial (typically bacterial) isolates. A study determined that the viral methods could be used in the analysis of shellfish tissue and that genotyping methods of F+ RNA phages were sufficiently developed whereas PCR detection of adenovirus was limited by uncertainties in excretion rates, ambiguous specificity, and molecular methodology. Antibiotic resistance/ multiple antibiotic resistance (MAR) analysis is a phenotypic technique examining antibiotic resistance profiles for isolated fecal indicators. Current methods for monitoring the quality of growing waters rely on bacterial indicators of fecal contamination. These organisms are general indicators of sanitation, not of the occurrence of pathogens, and knowledge of their presence alone may not allow adequate management of the shellfish-growing waters.
Key Concept Ranking
- Type III Secretion System
Classified U.S. shellfish-growing waters for 1995 a
Examples of state contribution to oyster harvest in 1995 a
Examples of state contributions to clam harvest in 1995 a
Pathogenic microorganisms found to accumulate in bivalve molluscs
Overview of shellfish harvest area classification criteria used in the European Union and the U.S. a