This part of ISO 21528 specifies a method, without pre-enrichment, for the enumeration of Enterobacteriaceae. It 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. Enumeration is carried out by counting colonies in a solid medium after incubation at 37 °C (or 30 °C)1). This technique is recommended when the number of colonies sought is expected to be more than 100 per millilitre or per gram of the test sample.