Absolute bacterial cell enumeration using flow cytometry.

The ability to obtain absolute cell concentrations is only available for selected flow cytometers, this study describes a method for accurate enumeration that is applicable to basic flow cytometers without specialized counting features. By demonstrating the application of the method to count E. coli, we raised points of consideration for using this FCM counting method and aim to lay the foundation for future work that uses similar methods for different bacterial strains.