Bacteriological analysis of drinking water from 100 families of Lahore by membrane filtration technique and chromagar

ABSTRACT

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 drinking water from some areas of Lahore by the Metnbrane Filtration Technique [MFT] using CHRO-Magar. Using this technique in one step a much large volume of water can be evaluated quantitatively 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. 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 CHRO Magar 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 2OE and confirmed by Eijkman test. Escherichia coli was grown from 42% samples [all Eijkman positive]. Coliform organisms were grown from 54% specimens. It was alarming that 59% of drinking water was unsatisfactory for human consumption