Methodology for screening bottled water for the presence of indicator and pathogenic bacteria
2000
Warburton, D.W.
At present in Canada, analysis of bottled water includes the use of pour plates for determination of aerobic colony counts (ACC); most probable numbers (MPNs) for the determination of coliforms and Escherichia coli; and filtering of 100-ml aliquots of the water for the determination of Aeromonas hydrophila and Pseudomonas aeruginosa. Generally, such analyses of bottled water products are time-consuming, costly, and often pointless as properly manufactured bottled water (especially those treated with ozonation and carbonation) will contain little or no bacteria. The ideal analysis would include the use of an enrichment broth that would resuscitate injured bacteria and allow them to multiply in the presence of an indicator system that would detect the presence of 'indicator micro-organisms' such as coliforms and/or pathogens. The use of such a broth would simplify the analyses and reduce costs associated with the testing of bottled water. The present study compared the recovery of stressed or low numbers of indicator and pathogenic bacteria from bottled water by i) determining if the standard method for coliforms/E. coli would isolate other indicator micro-organisms; ii) comparing the use of presence absence broth, nutrient broth and buffered peptone water as resuscitation/isolation broths; and iii) comparing recovery of indicator micro-organisms on a variety of selective agars. Its purpose was to make recommendations concerning the methodology for analysing bottled water; and to subsequently make recommendations as to the 'best' indicator for bottled water. Recommendations for the use of resuscitation broths in screening procedures are presented.
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