Development of a Simple Methodology to Establish the Presence of Coliforms in Water for Human Consumption and its Correlation with the Multi-Tube Fermentation Method (NMP)

Abstract

A simple field method was evaluated to determine the presence of total coliforms in water. For this study, a total of 280 water samples from the Unified Food and Drug Control Laboratory (LUCAM) and the Institute of Nutrition of Central America and Panama (INCAP) were analyzed.   The DAT-PA method (disc water test-presence/absence) and the standard Multiple Tube Fermentation (NMP) method were applied to each sample to validate the test.   The DAT-PA method was evaluated at two temperatures: 36°C ± 1 and 25°C = 1, being optimal for the growth of total coliforms. transport conditions, storage and stability were also evaluated, noting that both ambient and refrigeration temperatures (25°C and 8"C) allow the stability of the medium to be maintained for three months, taking care not to expose it to light, since this it deteriorates the disc To handle the test in a simple way, the use of sterile plastic bags was evaluated, which allow the DAT-PA disc to be kept in optimal conditions and at the same time it does not take up much space when stored.   The methods were statistically compared, obtaining a very good correlation with the reference method of Multiple Tube Fermentation (NMP). The sensitivity was 93% and the specificity was 95%.   It is concluded that it is a sensitive and specific qualitative method that can be applied for monitoring water, since it was designed for the use of the population that does not have infrastructure resources and trained personnel to carry out the bacteriological examination of water.