ISO/NP TS 27168

Water quality — Detection of Escherichia coli by real-time reverse transcription-polymerase chain reaction (RT-PCR)

Апстракт

This document specifies a method for the detection of 16S ribosomal RNA (16S rRNA) of Escherichia coli (E. coli) in drinking water using real-time reverse transcription-polymerase chain reaction (RT-PCR) based on a defined Ct-value (cut-off point).
This document is applicable to drinking water, and it can be applied to other water matrices if the appropriate validation of performance of this method has been undertaken by the laboratory prior to use.
The presence or absence of E. coli 16S rRNA is detected with a relative limit of detection level of 1 colony forming unit (cfu)/100 ml, unless the nature and/or content of suspended matter and/or accompanying flora in the matrix interfere with the efficiency of the real-time RT-PCR reaction. If such interference adversely effects the detection limit, its presence can be determined by using an internal process control.
The genetic target used by this method is not fully specific for E. coli. Consequently, closely related Escherichia species (e.g. E. fergusonii, E. marmotae, E. ruysiae) and Shigella species cannot be distinguished and will be detected by this method.