Recommended modification of dilution procedure used for bacteriological examination of shellfish.

The dilution procedure recommended by the American Public Health Association for use in bacteriological analysis of shellfish samples may cause an underestimation of the number of bacteria in shellfish. Modifications of that procedure to include preparation of the first dilution of the shellfish homogenate on a weight rather than a volume basis, and the inoculation of 1 g portions of the shellfish from a dilution of the homogenate, have been shown to significantly increase the recovery of fecal coliform bacteria from oyster samples. It is recommended that these modifications be adopted by the American Public Health Association.