Microbial indicators, in particular coliform bacteria including Escherichia coli and Enterococci have been established for detecting fecal contamination in water. These indicators, used to assess the potential public health risk of drinking water and their presence or absence, are key elements of most drinking water quality guidelines. Approved traditional methods for indicator organisms detection include the multiple-tube fermentation (MTF) technique and the membrane filter (MF) techniques were compared with the multiplex PCR technique. The multiplex PCR technique was optimized to use a combination of three set of different primers. The first set is for amplification of 876 bp from lacZ gene present in all coliform bacteria including E. coli, the second set is to amplify 147 bp of uidA gene specific for E. coli. While the last set produces 112 bp of tuf gene which is specific for all Enterococci. Multiplex PCR technique was shown to be an effective, sensitive and rapid method for the simultaneous detection of these three microbiological indicators in contaminated water. The optimized multiplex PCR was used for detection of pollutant microorganisms and evaluate three water treatment plants (El-Rahmna – El-Adlyia – El-Bostan) in Damietta County, Egypt.

Keywords: Indicator bacteria, multiplex PCR, LacZ, uidA, tuf.