This part of ISO 21528 specifies a method, with enrichment, for the detection of Enterobacteriaceae. It is applicable to ¾ð products intended for human consumption and the feeding of animals; and ¾ð environmental samples in the area of food production and food handling. Enumeration is carried out by calculation of the most probable number (MPN) after incubation at 37 °C (or 30 °C) ) in liquid medium. This method is applicable ¾ð when the microorganisms sought are expected to need resuscitation by enrichment; and ¾ð when the number sought is expected to be in the range 1 to 100 per millilitre or per gram of test sample. A limitation on the applicability of this part of ISO 21528 is imposed by the susceptibility of the method to a large degree of variability (see Clause 11).