scope:

This document specifies a method for the enumeration of Pseudomonas aeruginosa in water. Themethod is based on the growth of target organisms in a liquid medium and calculation of the mostprobable number (MPN) of organisms by reference to MPN tables.This document is applicable to a range of types of water. For example, hospital waters, drinking waterand non‐carbonated bottled waters intended for human consumption, groundwater, swimming pooland spa pool waters including those containing high background counts of heterotrophic bacteria.This document does not apply to carbonated bottled waters, flavoured bottle waters, cooling towerwaters or marine waters, for which the method has not been validated. These waters are, therefore,outside the scope of this document. Laboratories can employ the method presented in this documentfor these matrices by undertaking appropriate validation of performance of this method prior to use.The test is based on a bacterial enzyme detection technology that signals the presence of P. aeruginosathrough the hydrolysis of a 7‐amino‐4‐methylcoumarin aminopeptidase substrate present in a specialreagent. P. aeruginosa cells rapidly grow and reproduce using the rich supply of amino acids, vitaminsand other nutrients present in the reagent. Actively growing strains of P. aeruginosa have an enzymethat cleaves the 7‐amido‐coumarin aminopeptidase substrate releasing a product which fluorescesunder ultraviolet (UV) light. The test described in this document provides a confirmed result within24 h with no requirement for further confirmation of positive wells.