Is it time we revisit regulatory expectation that we obtain microbial identifications when using a non-growth-based monitoring method?

19 January 2024
Fill Finish
Margit Franz-Riethdorf
Global Change Facilitator

Bio-fluorescent particle counters (BFPCs) allow the detection and enumeration of microorganisms in the environment and rely on intrinsic fluorescence detection instead of growth – this constitutes a paradigm shift in microbial monitoring within aseptic manufacturing. BFPC systems fall into the category of rapid methods, which are encouraged by the new EU Annex 1.

This is why the Modern Microbial Methods Collaboration (M3) wanted to explore the advantages of using a BFPC in a Grade A aseptic processing environment and why germ identification cannot be expected when switching to a non-growth based method, such as a BFPC, which does not yield a microbial isolate.

The M3 Collaboration has documented its conclusions in an opinion piece in the PDA Letter on revisiting Regulatory Expectations for Micro ID in  Grade A environments for non-growth based methods.

Published in the PDA Letter, the paper discusses issues such as:

  • The benefits and limitations associated with the transition to non-growth-based air monitoring methods, like BFPCs
  • The fact that information about the microbial flora and the ability to perform trend analysis are still available without BFPC identification in Grade A areas
  • Why a shift in mindset for microbial identification requirements from BFPC in Grade A environments is needed.

The authors believe the advantages of continuous monitoring in Grade A using BFPCs are so overwhelming in improving sterility assurance that when moving from once-per-shift confirmatory testing to in-process monitoring, industry can forgo isolating and identifying microbial isolates in a Grade A environment.

The team’s experience indicates that the value of microbial identification in Grade A has been over-emphasized by regulators and industry and should not be a GMP requirement in situations where more advanced methods are used and that deliver better process knowledge and control.

This article is one of a series published by the M3 Collaboration, which consists of BioPhorum’s Alternative and Rapid Microbiological Methods Bio-Fluorescent Particle Counting team, the Kilmer Community Rapid Microbiology Methods group, the Process and Environmental Monitoring Methods (PEMM) working group and the Online Water Bioburden Analyzer (OWBA) group.

The M3 Collaboration’s previous articles include an Initial Evaluation Roadmap for Modern Microbial Methods, the Challenges Encountered in the Implementation of Bio-Fluorescent Particle Counting Systems as a Routine Microbial Monitoring Tool, and a piece on Understanding the Non-equivalency of Bio-fluorescent Particle Counts versus the Colony-forming Unit.

For more information, download the paper here and contact Margit Franz‑Riethdorf, Global Change Facilitator, at

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