Aims: To use BioBallTM
cultures as a precise reference standard to evaluate methods for enumeration
of Escherichia coli and other coliform bacteria in water samples.
Methods and Results: Eight methods
were evaluated including membrane filtration, standard plate count (pour
and spread plate methods), defined substrate technology methods (ColilertTM
and ColisureTM), the most probable number method and the Petrifilm
disposable plate method. Escherichia coli and Enterobacter aerogenes
BioBallTM cultures containing 30 organisms each were used. All
tests were performed using 10 replicates. The mean recovery of both bacteria
varied with the different methods employed.
Conclusions: The best and most
consistent results were obtained with Petrifilm and the pour plate method.
Other methods either yielded a low recovery or showed significantly high
variability between replicates.
Significance and Impact of the Study: The
BioBallTM is a very suitable quality control tool for evaluating
the efficiency of methods for bacterial enumeration in water samples. |