Thursday 28 December 2023

Not all plate counting technologies are the same


While rapid microbiological methods have advanced, most microbiology laboratory tests remain reliant upon assessing microbial growth on agar plates. Discrepancies with plate counting, together with the limitations of human vision, have led to regulatory concerns to the extent that the U.S. FDA Q&A document on data integrity recommends “double plate counting” using two independent analysts. Issues with plate counting such as the following occur periodically in FDA warning letters.


Not all plate counting technologies are identical and some struggle with mixed cultures or growth effects that lead to merged colonies. What is important is the appropriate selection and qualified adoption of automated digital capture colony counters within the pharmaceutical microbiology laboratory.


This article considers how such devices can be qualified and how data integrity concerns can be addressed.



Sandle, T. (2023) Not all plate counting technologies are the same, Outsourced Pharma, May 2023:


Also in:


BioProcess Online:

Pharmaceutical Online:

Biosimilar Online:


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

No comments:

Post a Comment

Pharmaceutical Microbiology Resources

Special offers