EN 17141: New Cleanroom Contamination Control Standards

Efforts are underway to harmonize the approach to cleanroom contamination control of microbes in air and on surfaces, with particles and other contaminants in air and on surfaces

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The new European Standard EN17141:2020 was issued in 2020 and supersedes two existing standards (ISO 14898 parts 1 & 2) for cleanroom contamination control that had limited application. EN17141, valid in Europe with the existing standards currently still applicable elsewhere, covers clean controlled environments and applies to cleanrooms, clean zones, controlled zones, clean areas, and clean spaces. Its aim is to provide updated guidance and further information on best practice for establishing and demonstrating cleanroom contamination control of airborne and surface microbiological contamination in clean controlled environments.

Its aim is to help increase the effectiveness of risk management associated with microbial contamination, improve efficiency, and provide users with new methodology and understanding to derive a system of microbiology control.

To establish microbiological control, it is important to understand what risk is, using an approach based on Quality Risk Management (QRM) principles. Risk can be defined as the combination of the probability of occurrence of harm and the severity of the harm. An effective quality risk management approach can ensure high quality of product to the patient by providing a proactive means to identify and control potential quality issues during manufacturing. This new cleanroom contamination control standard is relevant to several applications with particular use for pharmaceutical, biopharmaceutical, medical device, and other industries that use these environments (e.g., life science and food). It is important to note that this standard is limited in scope to viable microbiological contamination and excludes any considerations of endotoxin, prion, and viral contamination.

Understanding risk of the organism of interest

Cleanroom contamination can come from a variety of sources e.g., personnel, materials, equipment, air, and the surrounding environment, (although water is excluded from this document), and the evaluation of risk to quality should be based on scientific knowledge. It is important to be able to accurately identify any organisms of interest (or objectionable organisms) to assess the potential for causing contamination of the product or harm to the patient. There are many ways to characterize or identify microorganisms isolated from cleanroom environments (e.g., Gram stain, phenotypic, genotypic, etc.). Basic characterization such as Gram reaction gives general information about the likely source of the contaminant.

However, more information on what species the isolate is will help with tracking the route of transfer. Other commercially available methods of identification can provide species level identifications, but it is important to note that some cleanroom contamination control methods are not as accurate or precise as others (e.g., phenotypic method vs. genotypic methods). An identification that is as accurate as possible will aid in assessing the risk posed by that organism. It also ensures trending is accurate and investigations are based on the most accurate information.

In recent years Matrix Assisted Laser Desorption Ionisation Time of Flight (MALDI-TOF) microbial identifications have allowed for faster, more cost-effective identifications. And whilst this technology is not as accurate as sequencing, it has the potential to be much more accurate than phenotypic methods, due to analyzing ribosomal proteins that are closer to the DNA of the organism rather than analysis of biochemical reactions (such as fermentation, acid and salt tolerance metabolism, etc.). Whilst the cleanroom contamination control technology utilized for identification methods plays a role in the accuracy of the result, one aspect that is often overlooked is the library or database that the system relies upon to generate the ID. When an organism is not in the database of the system being used, it will not be identified correctly.

However, it is important to underline that when an identification system does not have sufficient coverage it does not always result in a “no identification.” It may also result in an incorrect identification, meaning any further risk assessment will be based on incorrect information, which potentially is worse than no identification at all.

The standard requires that microorganisms of interest should be identified, and survival possibility considered. A microorganism of interest is defined as an organism that is harmful to the product, the process, or the patient. It is especially important to be able to identify isolates to determine if there may be some resistance to steps taken to remove contamination, e.g., disinfection regime or sterilization. Depending on the process there are specific organisms that can pose challenges. For example, spore formers can challenge cleaning programs; Pyronema domesticum has been known to withstand (1) ethylene oxide sterilization cycles and Deinococcus species have been shown (2) to withstand large doses of irradiation, enough to withstand doses used for sterilization of pharmaceutical and medical device products (typically <25kGy). It is vital to be able to identify the presence of such organisms from pre-sterilization bioburden to reduce risk of contamination of final product.

Demonstrating Cleanroom Contamination Control: Trending data

Data generated from the Environmental Monitoring program should be analysed to help identify any adverse trend that may require corrective or preventative action (CAPA). Trending data allows for proactive action before any issues arise. The data should be reviewed by a competent microbiologist to identify any possible issues. Accurate identifications are vital to ensure that the data analysed for trends is reliable for subsequent decision and action. Inconsistent identification methods that may generate different names for the same isolate or fail to identify at all will make trending ineffective. The tool used for managing data should allow for easy identification of trends but also allow for alerts when an organism of interest is identified.

Out-of-Specification Investigations

The objective of out-of-specification (OOS) investigations is to determine the risk to the product or process, determine the likely source of the cleanroom contamination (tracing the same species via the historical database), and help define the appropriate CAPA. Investigations should be prompt, thorough, and scientifically sound to determine the cause and appropriate corrective action. When identifying microbial isolates during an OOS investigation the ID method should be as accurate as possible to ensure that any decisions or actions taken are not based on inaccurate identifications which are considered to be more of a risk than a no identification. (3)

Conclusion

The new standard has an emphasis on a QRM approach. Successful cleanroom contamination control monitoring of environments requires having a system in place to detect microbiological contamination and accurately identify, to species level, organisms isolated. Modern, scientifically sound methods for identifying isolates will allow for proactive action to ensure any risks are managed before any contamination occurs.

Duncan Barlow is the Europe and Asia Pacific Technology and Market Development Manager for Charles River Laboratories’ Microbial Solutions division supporting customers who are implementing microbial identification solutions across Europe and Asia. He has over 20 years of experience with implementing testing, sales, and technology across the pharmaceutical, food, and clinical industries. Duncan is also familiar with endotoxin testing, rapid microbiological methods, and environmental monitoring.

1. Lampe CM, Hansen JM, Rymer TM, Sargent H. Sterilization of products contaminated with Pyronema domesticum. Biomed Instrum Technol. 2009 Nov-Dec;43(6):489-97. doi: 10.2345/0899-8205-43.6.489. PMID: 20041540.

2. Rainey FA, Ray K, Ferreira M, Gatz BZ, Nobre MF, Bagaley D, Rash BA, Park MJ, Earl AM, Shank NC, Small AM, Henk MC, Battista JR, Kämpfer P, da Costa MS. Extensive diversity of ionizing-radiation-resistant bacteria recovered from Sonoran Desert soil and description of nine new species of the genus Deinococcus obtained from a single soil sample. Appl Environ Microbiol. 2005 Sep;71(9):5225-35. doi: 10.1128/AEM.71.9.5225-5235.2005. Erratum in: Appl Environ Microbiol. 2005 Nov;71(11):7630. PMID: 16151108; PMCID: PMC1214641.

3. Parenteral Drug Association Technical Report 88. Microbial Data Deviation Investigations in the Pharmaceutical Industry (2022)