BACTERIOLOGICAL ANALYSIS OF DRINKING WATER FROM 100 FAMILIES OF LAHORE BY MEMBRANE FILTRATION TECHNIQUE AND CHROMAGAR

Introduction: Water borne diseases are caused by pathogenic microorganisms. In Pakistan, the availability of safe water is only 40% to 60%. Therefore it becomes imperative to determine the bacteriological status of drinking water. A few laboratories perform such an evaluation and, that too, by the old method technique i.e Most Probable Number (MPN). We evaluated 100 samples of drin-king water from some areas of Lahore by the Membrane Filtration Technique (MFT) using CHRO-Magar. Using this technique in one step a much large volume of water can be evaluated quantita-tively in a short time and with ease. Use of CHROMagar straightaway confirms the presence of Escherichia coli which is accepted universally as the indicator of fecal contamination.Materials and Methods: It was a cross sectional study. A volume of 100 ml water was filtered under the vacuum pressure through Millipore membrane filters. After filtration, membrane filters were placed on CHROMagar and incubated at 35C for 24 hr. Escherichia coli appeared as blue coloured colonies while coliforms yielded colonies of pink colour. Escherichia coli were further identified by API 20E and confirmed by Eijkman test.Results: Escherichia coli was grown from 42% samples (all Eijkman positive). Coliform organisms were grown from 54% specimens.Conclusion: It was alarming that 59% of drinking water was unsatisfactory for human consumption.