ISO 7251:1993

Microbiology — General guidance for enumeration of presumptive Escherichia coli — Most probable number technique

Gives general guidelines for the enumeration of presumptive Escherichia coli in products intended for human consumption or feeding of animals, by means of the liquid-medium culture technique and calculation of the most probable number after incubation at 35 °C or 37 °C (this temperature forming the subject of agreement between the parties concerned), then incubation at 45 °C. A limitation of the applicability is imposed by the susceptibility of the method to a large degree of variability.