Establishment of duplex-PCR assay for detection of Escherichia coli in drinking water

  Objective   To establish a duplex-PCR assay for the detection of Escherichia coli (E.coli) in drinking water and to assess detection results of the assay.

  Methods  First, the conservative sequence 16SrRNA gene of E.coli (E-16SrDNA) and the lactose operon LacI gene sequence (E-LACI) were selected as the two segments amplification gene of the duplex-PCR assay. According to the known sequence from the GenBank, the primers of the two segment genes were designed and synthesized, and duplex-PCR assay was established using the standard E.coli strain. Then, E.coli in drinking water samples was detected with both the duplex-PCR assay and the national standard method to evaluate the validity, reliability and prediction probability of the established assay.

  Results   For the duplex-PCR assay established, the minimum detection concentration of the E.coli in water samples was 40 colony forming unit (CFU)/L; the sensitivity was 66.7%; the specificity was 100%; the positive predictive value was 100%; the negative predictive value was 97.7%; and the consistent rate for the detection results versus those with the national standard method was 97.8%.

  Conclusion   The established duplex-PCR assay is of high validity and sensitivity and is suitable for rapid detection of E.coli in drinking water samples.