Evaluation of Petrifilm EC and HS for total coliforms and Escherichia coli enumeration in water

Abstract

Petrifilm™ EC and HS were compared to the MPN method to determine their efficacy to enumerate total coliforms and E. coli in 145 samples of water (76 water in natura, 69 drinking water). For water in natura, Petrifilm™ HS and EC showed good correlation with MPN method. In chlorinated water (< 20 col/100 mL and negatives) the agreement was low. For E.coli enumeration, Petrifilm™ EC showed a good correlation with MPN method. The results indicated that Petrifilm™ EC and HS are accurate to enumerate coliforms and E. coli in water when the expected counts are higher than 20/100 mL.