Rapid detection and enumeration of coliforms and Escherichia coli in River Nile using membrane filtration technique

The purpose of this investigation was to compare Rapid Hicoliform Agar® (RHA, Himedia, India) with the conventional m-Endo Agar (DIFCO, Michigan, USA) for detection and enumeration of Total Coliforms (TC) and with the conventional Seven Hour Fecal Coliforms Agar (7hFC) for detection and enumeration of Escherichia coli using Membrane Filtration (MF) in River Nile water, Egypt. Sixty samples were collected (five samples per month) from five regions (Kafr El-Elw, El-Maasara, El-Giza, Embaba and El-Galatma) during one year (December 2005-November 2006). The results showed that total coliforms counts ranged from 103 to 104 CFU*100ml-1 using RHA but using m-Endo Agar the counts were around 104 CFU*100ml-1. Escherichia coli counts ranged from 103 to 104 CFU*100ml-1 using 7hFC Agar, while using RHA the counts ranged from 103 to 104 CFU*100ml-1. Statistical analysis showed that there was no significant difference (p=0.423) between total coliforms counts using m-Endo Agar and RHA media, also, there was no significant difference (p=0.546) between fecal coliforms (E. coli) counts using 7hFC Agar and RHA media. We conclude that RHA is a potential alternative medium for detection and enumeration of total coliforms and E. coli at the same time and the same Petri dish within 24h. Also, RHA medium was a very sensitive medium, which did not require any confirmatory tests and secured rapid recovery of total coliforms or E. coli.