Clean room : mapping of microbiological samples of the environment using a Failure Mode an Effect Analysis (FMEA) method

Introduction
Environmental microbiological controls in Clean Rooms (CR) are key elements for monitoring the compliance of an aseptic production process. Upcoming work and changes to the layout of our CRs have led us to review the relevance of our sampling plans. The objective of this work was to conduct an analysis of our circuit, to map the areas at risk of microbiological contamination and, thus, to adapt our sampling plans accordingly.

Method
A FMEA method was used to assess the risk of contamination in two grades C CR’s. It brought together 6 members of the pharmaceutical and paramedical staff. Each CR was delimited into several zones and the risks of contamination were listed then rated according to numerical scales of severity (S), probability (P), non-detectability (D) and risk priority number (C= PxSxD).

Results
Within the two CRs, 17 zones have been delimited. The criticalities ranged from 2 to 80 and made it possible to classify the risks according to low [2-25], moderate [26-45] or high [46-80] criticality. 5 areas presenting more than 2 high criticality risks have been classified as areas with a high risk of microbiological contamination (e.g. handling benches). 7 areas presenting only 1 high criticality risk have been classified as areas with a moderate risk of contamination (e.g. isolators). The others have been classified as areas with a low risk of contamination.
Compared to our current sampling plan, our study highlighted that the high risk of microbiological contamination areas benefited from reinforced sampling by weekly sedimentation plate and monthly contact-plate. The results of the microbiological samples taken over the year 2021 went into this direction and identified these areas as those where the contaminations were the highest (6 CFU/week on average in the high risk of contamination areas).
Of the 7 zones at risk of moderate contamination 5 zones are subject to at least one type of sampling while 3 zones are not taken.

Discussion-Conclusion
This study confirmed the relevance of the current control points and highlighted the areas for which controls must be organized. A new application of this method will allow us to redefine a sampling plan in another CR in which a complete change of organization and equipment will be implemented.

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