Enterobacteriaceae MPN (Most Probable Number)
Enterobacteriaceae Petrifilm*
Enterobacteriaceae Pour*

Method References

Microbiology of the food -Horizontal method for the detection and enumeration of Enterobacteriaceae ISO 21528 
3M™ Petrifilm™ Enterobacteriaceae Count Plate Interpretation Guide
Compendium of Methods for the Microbiological Examination of Foods

Sample Size


Estimated Turn Around Time

Petrifilm/Pour - 24 Hours
MPN - 48 hours (If presumptive, additional 24-48 hours)

Reporting Unit

Petrifilm/Pour: cfu/g, cfu/mL, cfu/sampled area

Method Description

Petrifilm/Pour: Samples are prepared and dilutions made. The samples are then plated on media and incubated based on method specifications. After incubation plates are read and results generated based on countable range.
MPN: Samples are prepared and 3 dilutions (3 tubes each) are made. Samples are then incubated and struck to agar plates after 18 hours. The agar plates are incubated for 24 hours and read for growth. If colonies are observed they are then plated for further confirmation work.

Additional Information

Enterobacteriaceae is often used as an indicator organism. An indicator organism is often described as an organism whose presence or level indicates the potential for future spoilage or as a “surrogate” organism, for example, those organisms that model the behavior of pathogens under certain conditions.
These procedures enumerate the number of Enterobacteriaceae in a sample using a pour plate, petrifilm, or most probable number (MPN) method.