3M Petrifilm coliform count plates are available from 3M Food Safety (Microbiology) that can easily differentiate coliforms from non-coliforms.
3M Petrifilm coliform count plates offer 24-hour result for both positives and negatives with no need for confirmation, whereas VRBA and MPN methods require confirmation and a period of at least another 24 hours.
In Petrifilm coliform count plates, the combination of red colour and presence of gas easily identifies a colony as a coliform. The VRBA method does not use gas as an indicator.
3M Petrifilm coliform count plates are more precise than the MPN method and the direct count gives smaller confidence intervals. Additionally, the 3M process is faster than MPN with MPN taking at least 48 hours.
Automated reading is available using Petrifilm plate readers.