ISO/TS 16649-3:2005 specifies a horizontal method for the enumeration of beta-glucuronidase-positive Escherichia coli, by means of the liquid-medium culture technique and calculation of the most probable number (MPN) after incubation at 37 °C, then at 44 °C.

This Technical Specification is applicable to products intended for human consumption and the feeding of animals, and environmental samples in the area of food production and food handling.

The method is suitable for the enumeration of cells of Escherichia coli that may have been subjected to stress arising from dehydration, freezing, exposure to a saline (such as marine) environment or damage by disinfectants such as chlorine-containing products.