COLIFORM BACTERIA IN SEA WATER AND SHELLFISH: II. THE E. C. CONFIRMATION TEST FOR ESCHERICHIA COLI

Abstract
Recently there has been considerable interest in Canada and the United States in the development of an effective, simple test for the estimation of Escherichia coli densities in shellfish and shellfish-growing waters as a better indication of "faecal" pollution than that provided by the coliform group. The fidelity of the E.C. confirmation test for the determination of E. coli densities was evaluated in 15 shellfish-growing areas which were classified as "polluted" or "unpolluted" according to generally accepted criteria. Coliform strains were isolated from 2765 E.C. gas positive confirmation test cultures and identified by IMViC tests. The mean fidelity of the test, as an indication of the presence of E. coli, was circa 90 per cent; contrary to expectations, however, the per cent recovery of E. coli was higher in unpolluted areas than in polluted areas, and varied considerably from region to region. Aerobacter aerogenes types I and II were the most common other E.C. gas positive coliform biotypes found. The usefulness of the confirmation test and the sanitary significance of these data are discussed.

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