Publication Abstract

Modification of the standard UK method for the enumeration of Eschericha coli in live bivalve molluscs

T.D. Donovan, S. Gallagher, N.J. Andrew, M.H. Greenwood, J. Graham, J.E. Russell, D. Roberts and R.J. Lee

The standard method for counting Escherichia coli in live bivalve molluscs is labour intensive and takes three days to obtain a result. Modifications to the standard method were investigated in a collaborative trial conducted in five centres. No significant difference was found between results based on the presence of acid at 24 hours (h) in first stage tests and those based on the presence of acid and gas after 48 h (standard method). The use of the chromogenic medium BCIG (5-bromo-4-chloro-3-indolyl- b-D glucuronide) agar incubated at 44°C to confirm first stage tests was also found to give equivalent results to conventional confirmation tests. The preferred, modified method removes the presence of gas as a criterion of detection, uses a chromogenic agar medium to confirm the presence of E. coli, and gives results within 48 h. A distribution of simulated samples and selected strains of E. coli to other laboratories using the PHLS external quality assurance scheme for shellfish found no significant difference between results obtained by the standard and modified methods.

Reference:

T.D. Donovan, S. Gallagher, N.J. Andrew, M.H. Greenwood, J. Graham, J.E. Russell, D. Roberts and R.J. Lee, 1998. Modification of the standard UK method for the enumeration of Eschericha coli in live bivalve molluscs. Communicable Disease and Public Health, 1(3): 188-196