Aquagenx CBT and Colilert Comparative Study in Kenyan Households

The authors of this paper published in the American Journal of Tropical Medicine and Hygiene compared the concentrations of Escherichia coli quantified with IDEXX Colilert™ and the Aquagenx Compartment Bag Test (CBT) in source water and household stored drinking water (SDW) in 35 households in western Kenya. In low-resource settings, the CBT provides comparable assessments of E. coli concentrations to Colilert.

Also investigated were the associations of the perceptions of organoleptic properties and overall quality with ≥ 1 MPN/100 mL E. coli in SDW. Participants who rated the taste or smell of their SDW “< 5” on a 1 = “poor” to 5 = “excellent” Likert scale were 8.71 or 7.04 times more likely, respectively, to have ≥ 1 MPN/100 mL E. coli. Organoleptic properties are innate, albeit imperfect, indicators of fecal pollution in water. Within their shared quantification range, concentrations of E. coli enumerated with Colilert and the CBT were similar and had a significant correlation coefficient, 0.896 (95% confidence interval = 0.691–1.101). The methods had moderate agreement within the World Health Organization’s health risk levels (Cohen’s Kappa coefficient = 0.640).