Identification of family Enterobacteriaceae using a three tube method.

Four hundred isolates of Gram Negative bacilli from different samples were tested by three tube method and conventional tests. An overall agreement between the two methods was 89.5%. Non-agreement was in respect of less stable tests like gas production and motility. This does not reflect adversely on the efficacy and suitability of the method. The three tube method is simple, rapid, economical and accurate, saving both time and material.