Observations on the use of a medium detecting β‐glucuronidase activity and lactose fermentation for the simultaneous detection of Escherichia coli and coliforms

Abstract

A study of the use of a recently described single membrane medium for the simultaneous enumeration of Escherichia coli and coliforms has shown similar E. coli confirmation rates (92%) for both membrane lauryl sulphate broth (MLSB) and membrane lactose glucuronide agar (mLGA). Of the presumptive E. coli examined, a higher proportion of those examined from MLSB subsequently produced acid and gas from lactose peptone water and indole from tryptophan than on mLGA. These results differ in some respects from those presented in the original paper and may therefore be of interest to those workers involved in the detection of E. coli in water. Further investigation showed that mLGA which has been stored under aerobic conditions was less efficient than freshly‐prepared medium in recovering coliforms and that the size of the colonies obtained on stored medium was sometimes much smaller than those found on freshly‐prepared medium. Copyright © 1994, Wiley Blackwell. All rights reserved