Objective: To evaluate a simple low cost method for measuring hand contamination as an objective assessment of handwashing practices.
Method: As part of a larger randomized controlled trial of handwashing promotion with soap conducted in squatter settlements of Karachi, Pakistan, a randomly selected subset of 52 mothers in households receiving soap and handwashing promotion and 28 mothers in control households directly pressed three fingers of their right hand onto MacConkey agar plates on weekly unannounced visits from April to September 2002, and monthly from October 2002 to March 2003. The MacConkey plates were incubated at 44 degrees C for 24 h, and evaluated for growth of thermotolerant coliform bacteria.
Results: The proportion of samples that had detectable thermotolerant coliforms (50%) was similar in households that received soap and control households (52%, P = 0.40). In the week after evaluation of the mothers' hands, the proportion of households that reported diarrhoea was similar regardless of whether or not the mother had thermotolerant coliforms detected by direct finger imprint (18.6%vs. 19.1%, Relative Risk 0.99, 95% CI 0.96, 1.03).
Conclusions: A three finger direct imprint test using MacConkey agar for thermotolerant coliforms was not a useful method to assess regular handwashing practices with soap in Karachi. Developing better measures of handwashing behaviour remains an important research priority.