Direct detection of bacterial faecal indicators in water samples using PCR

The presence of enteric pathogens in water resources represents a serious risk for public health. Therefore, their precise detection, and especially detection of E coli, which is obviously regarded as the main indicator of faecal contamination of water, is an essential step in ensuring bacterial safety of water. Numerous PCR protocols for detection of E coli have been published to date. They are usually based on amplification of regions derived from lacZ (beta-D-galactosidase) and uidA (beta-D-glucuronidase) gene sequences. However, these methods are not universal enough for precise detection of all E coli strains found in water samples. We developed a novel triplex PCR method for detection of E coli in which cyd gene coding for cytochrome bd complex was co-amplified along with lacZ and uidA genes. Our triplex PCR approach significantly increases the specificity and reliability of E coli detection in water samples. This approach allowed us to distinguish Shigella flexneri from E coli. In addition, we were able to detect even non-coliform Klebsiella and Raoutella spp., some of which can also cause infections to humans.