ISO 11866-2|IDF 170-2:2005 specifies a method for the enumeration of presumptive Escherichia coli by means of a colony-count technique at 44 °C.

The method is applicable to milk, liquid milk products, dried milk, dried sweet whey, dried buttermilk, lactose, acid casein, lactic casein and rennet casein, caseinate and dried acid whey, cheese and processed cheese, butter, frozen milk products (including edible ices), and custard, desserts and cream.

The method specified in ISO 11866-2|IDF 170-2:2005 is the preferred method for samples in which comparatively large numbers of presumptive Escherichia coli (more than 100 per gram or 10 per millilitre) are suspected.