USP recommends revisions to proposed RMM chapters

In January, United States Pharmacopeia (USP) published revisions to previous drafts of chapters about using rapid microbiological methods (RMM), with a specific focus on short-life products.

<72> Respiration-Based Microbiological Methods for the Detection of Contamination in Short-Life Products

The changes for the proposed chapter the detection of contaminants in short-life products. With ‘significant’ revisions from previous versions, it is based on the version published in PF 46(6) as “Respiration-Based Rapid Microbial Methods for the Release of Short Shelf Life Products”.

According to USP, the previous proposal has been revoked and this updated version is replacing it. Its Microbiology Expert Committee suggested revisions including changing the title to “Respiration-Based Microbiological Methods for the Detection of Contamination in Short-Life Products”. ALso suggested was aligning it with existing USP chapters, via modifying the requirements of culture media selection and incubation temperature.

Furthermore, the committee suggested having additional requirements in the Method Suitability Test, including:

• Inoculation of test microorganisms at not more than 10 CFU
• Specification that the list of microorganisms in Table 1 is the minimal requirement. Inclusion of product- and processing-relevant strains and local isolates should be considered with appropriate risk-based justification.
• Specification that positive control and negative controls should be included in the suitability test
• Utilising a new safety margin concept to determine the longest time to detection.

<1071> Rapid Microbial Tests for Release of Sterile Short-Life Products: A Risk-Based Approach

USP noted that the proposal of this chapter is based on the version from 1 December 2019.

The Microbiology Expert Committee requested that the chapter title is changed to “Rapid Microbiological Methods for the Detection of Contamination in Short-Life Products—A Risk-Based Approach”.

USP called for the application of rapid microbiological methods to short-life products to be redefined.

The revision also suggested using a calculation to evaluate the probability of contamination and to define an adequate sample volume.

Alongside this, the committee proposed removing the limit of detection as the critical operation parameter when determining a risk-based microbiological method.

Moreover, it was advised that further guidance on the validation and suitability testing of the rapid microbiological method was included.

The revisions also proposed updating the example technologies in this chapter. The committee recommended this change so that the technologies align with the USP Microbiology Expert Committee evaluation: ATP bioluminescence, nucleic acid amplification, respiration, and solid phase cytometry.

Overall, these revisions highlight the need for greater clarity to support individuals and companies applying the guidelines, as well as a need to harmonise earlier recommendations and current drafts of the chapters, ultimately integrating USP’s current thinking.

The deadline to submit comments on the proposed chapter revisions on rapid microbiological methods is 31 March 2024.

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