Components of microbiological monitoring programmes

Microbiological monitoring of bivalve mollusc production areas by national or regional authorities is usually undertaken as part of a programme to classify the areas according to the perceived risk of the presence of pathogenic microorganisms based on the concentrations of faecal indicator bacteria present in the area. The indicator bacteria used are generally of the coliform group: total coliforms, faecal coliforms or E. coli depending on the requirements of the legislation which applies. Although a number of other faecal indicator bacteria have been used for other programmes (e.g. drinking or recreational waters) these have not generally been applied to the classification of shellfish harvesting areas. Figure 6.1 shows the proportion of samples positive for Salmonella spp. in different classes of shellfish harvesting areas in England and Wales. Other workers have showed a similar change in the occurrence of norovirus positives with