Detection of Six E. coli O157 Virulence Genes in Water Samples Using Multiplex PCR | ||||
| Egyptian Journal of Microbiology | ||||
| Article 11, Volume 47, Issue 1, December 2012, Page 171-188 PDF (867.05 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejm.2012.259 | ||||
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| Abstract | ||||
| ESCHERICHIA COLI O157 strains have emerged as important human enteric pathogens. E. coli O157 strains may be transmitted in a variety of ways, including drinking water, recreational water, and wastewater. One hundred and seventy five water samples were collected from different water sources from June 2010 to July 2011 and examined for classical bacterial indicators (total bacterial counts at 37oC and 22oC, total coliforms, fecal coliforms and fecal streptococci) and E. coli O157. Total coliforms (TC), fecal coliforms (FC) and fecal streptococci (FS) among the collected water samples were 83, 76 and 76 out of 175 (MPN- index/100 mL) with the incidence ratio of 47%, 43%, and 43%, respectively. Escherichia coli O157 was detected in water samples using HiCrome EC O157:H7 agar and multiplex PCR targeting six virulence genes {stx1 (Shiga toxin 1 gene), stx2 (Shiga toxin 2 gene), eae (intimin gene), hlyA (hemolysin gene), rfbE (O157 antigen gene), and fliC (flagellar antigen gene)}. The sensitivity test showed that the multiplex PCR amplified genes with a minimum of 100 CFU of E. coli O157. Conventional method using HiCrome media indicated that 57 out of 175 examined water samples (32%) contained E. coli O157. The multiplex PCR indicated that 60 water samples were positive for at least one of the six targeted virulence genes. The most prevalent virulence genes in E. coli O157 isolates were Shiga toxin 2 gene (stx2) (98%), intimin gene (eae) (98%) and O157 antigen gene (rfbE) (98%) followed by Shiga toxin 1 gene (stx1) (84%) then flagellar antigen gene (flic) (66%) while Hemolysin gene (hlyA) (0%) was not detected in any E. coli O157 isolates. | ||||
| Keywords | ||||
| E. coli O157; virulence gene; Multiplex PCR; water | ||||
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