Evaluation of a rapid method for E coli and thermotolerant coliforms in recreational waters Available to Purchase

The management of recreational beaches based on the standard methods for E coli or thermotolerant coliforms can present a challenge to public health officials. Typically there is a 30-48h delay between sample collection and availability of results. Bacteriological water quality can change significantly during this period. During 1995 and 1996, a rapid method, based on the production of glucoronidase by E coli or galactosidase by thermotolerant coliforms, was developed to shorten this delay. During the summer of 1997, the rapid method was compared to the standard membrane filtration technique for E coli. Using 563 comparisons, the correlation for E coli detected by the rapid method and membrane filtration yielded a r² = 0.89. The percent agreement between the methods based on the number of times both provided results above or below the provincial objectives of 100 E coli/100mL was 84.6%. Similar results were obtained for 1,168 comparisons of thermotolerant coliform data. Using the rapid method, results for samples collected in the morning are available by the afternoon of the same day. The rapid method not only allows for the prompt closure of beaches but also maximises the times when the beaches are open.