Isolation and detection of Escherichia coli O157 from potable water system of Lahore,Pakistan

This study was conducted to carry out the qualitative analysis of drinking water system of lahore,pakistan to detect the presence of escherichia coli o157. potable water samples were collected from different localities and analyzed by the most probable number tests (mpn). initially,42 strains that showed morphological resemble with e. coli were characterized by growing on eosine methylene blue (emb) agar. finally,13 e. coli strains that were non-sorbitol fermenters were selected and their taxonomic status was confirmed by using rapid™ one identification system. antibiotic sensitivity profiling of selected bacterial strains was also analyzed and majority were found to be resistant against ampicillin,erythromycin and carbenicillin. all sorbitol negative and biochmically identified e. coli strains were then subjected to serological testing using prolextm latex agglutination kit for detection of somatic antigen i.e.,o157. positive agglutination was recorded in all sorbitol non-fermenting strains except s7d and s7e indicating the presence of this virulent strain in drinking water supply system. analysis of biofilm formation revealed that s7d was the most effective either as single or in co-cultures (s2a+s7d) in the presence or absence of feso4. in conclusion,the detection of e. coli o157 from drinking water suggests a possible health threat in terms of diarrheal diseases and renal syndromes to the local community. © 2014 zoological society of pakistan.