Quantitative methods for studies on vaginal flora.

Three recently described methods for quantitative sampling of the bacterial flora of the vagina were evaluated and none proved satisfactory. In a third of the samples, paired swabs showed large differences between the two weights of vaginal secretion collected by this method, and the recovery rate of bacteria deliberately added to test swabs was unsatisfactorily low. A calibrated loop gave a wide variation in the amount of secretion collected, due to variations in density and viscosity of the secretion. When secretion was collected with a calibrated pipette, it was often difficult to expel the collected volume from the pipette for testing. The simple weight-based method was devised in which a loop was used to collect an undefined volume of secretion for weighting in a tube of transport medium before homogenisation and quantitative bacteriological testing. Initial assessment indicates this to be a satisfactory method for quantitative studies of the vaginal bacterial flora.