Escherichia coli testing and enumeration in live bivalve shellfish - Present methods and future directions

Abstract

A wide variety of pathogenic agents such as bacteria, viruses and parasites can be greatly concentrated in filter feeding bivalve molluscan shellfish (BMS), that are grown in faecally contaminated waters. Human health risks associated with the consumption of BMS are also compounded by the traditional pattern of consuming them raw or lightly cooked. Because of these well-established food safety risks, food legislation such as that in Europe stipulates that BMS production areas are monitored for faecal contamination and classified accordingly. In this review we provide information regarding the background and use of methods for determining and quantifying Escherichia coli (E. coli) in shellfish matrices, focussing on the Most Probable Number (MPN) based approach. This review also discusses other techniques for determining E. coli in food matrices, as well as specific tests across a range of other food microbiology applications. This information draws on several sources: published peer-reviewed reports, data derived from proficiency testing/ring trials, depuration and challenge studies, as well as specific examples from BMS classification and long-term monitoring studies. We also provide a discussion on possible avenues for future direction regarding testing methods in this food microbiology sector.

Keywords: Bivalve shellfish; Classification; E. coli; Impedance; MPN.