AWWA WQTC63955

The European Guideline 98/83 stipulates mCP agar as the reference method for recovering C. perfringens from drinking waters. However, previous studies indicated that other media are more suitable for C. perfringens count from relatively unpolluted waters, part-treated waters or groundwaters. PACp® is a fluorogenic culture medium based on acid phosphatase activity and was designed in our laboratory for the detection of C. perfringens in water, without the need of further confirmation. The results previously suggested that PACp® is an adequate medium for presence-absence determination of C. perfringens in water. Thus, the main objective of this work was to investigate the ability of this fluorogenic medium as an alternative approach using the most probable number method for recovering C. perfringens in drinking water samples. To that end, the study used marginally chlorinated water samples for generation of chlorine injured organisms using both river water and sewage effluent as the source of target organisms. Also, reference material and surface water samples were used. The samples were analyzed by means of the most probable number method with 50 wells using PACp® medium. C. perfringens recovery was also performed on mCP agar (Cultimed, Panreac), according to Directive 98/83, and on TSC agar (Merck) also using membrane filtration technique. Both "presumptive" wells from PACp® and colonies from mCP agar and TSC agar were examined for Gram stain, sulphite reduction, lactose fermentation, "stormy fermentation", motility, gelatin liquefaction and nitrate reduction. The analysis of the data indicated that the PACp® could be used as alternative methods for detecting and recovering C. perfringens in treated water. Includes 22 references, tables, figures.