Compatibility Rate of Three Laboratory Methods for Enumerating Thermo-tolerant Coliforms in Water Resources

It is essential to evaluate the methods applied in the detection and enumeration of bacterial indices used in water quality management. The present study (descriptive and analytical in nature) aimed to determine the correlation and compatibility rates of the detection methods of multiple tube fermentation (both traditional and direct techniques) using EC Broth and plate count in special fecal coliform culture media. The objective was to identify the one method among these which is economical, effective, rapid, and easy to use under emergency conditions. Pour plate count using eosin-methylen blue (EMB) was evaluated in comparison with the traditional and direct multiple tub fermentation (MTF) as techniques used in enumerating thermo-tolerant bacteria and Escherichia coli in water resources.. 14 samples were required for the pilot study. However, 70 samples were analyzed to obtain a higher level of accuracy through three microbial laboratory methods. In evaluating raw water collected from wells, springs, and rivers as well as the effluent from wastewater treatment plants, a high Pearson correlation was found for enumerating thermo-tolerant bacteria. The results revealed that the majority of the samples contained thermo- tolerant coliforms. Based on the correlation coefficients calculated among the three methods, economic considerations, test duration, and time to yield results the plate count, the direct MTF, and the traditional MTF may be ranked in a descending priority order from the viewpoint of bacterial quality assessment of water resources for the emergency conditions and irrigation purpose