Choosing the right disinfectants for cleanrooms and factors influencing their performance

To maintain a high level of cleanliness, a sound cleaning and disinfection system needs to be established and controlled. This is key to manufacturing quality products, meeting regulatory requirements and ensuring patient safety. Sascha Rother of basan highlights basic considerations regarding disinfectant choices and provides guidance on the factors impacting the performance of cleaning operators.

The rule of thumb is that no disinfectant will tick all the boxes. The best approach is to pick the right disinfectant (or a combination thereof) for the right application and prevailing in-house flora.

Some observations made in South Africa are that manufacturers of pharmaceutical and nutraceutical products will only use one disinfectant or two products with a similar chemical composition and basically the same kill range. In some instances, manufacturers will only apply a sporicidal product. According to EC GMP and ISO 13408.3 Part 11.1.8 rotating two different disinfectants to reduce the potential risk of developing resistant strains should form part of your regime.

Environmental monitoring is required to understand the in-house flora and decide on the most suitable disinfectants. The daily disinfection should be a biocide that has broad-spectrum efficacy effective against vegetative organisms, e.g. gram-negative and gram-positive bacteria. The rotational product is commonly a sporicidal product. The choice and frequency are determined based on the prevailing organisms. The usage of sporicidal products should be minimised as they can potentially damage surfaces, require special PPE or leave residues if not removed.

Did you know?

Grade A/B cleanrooms require a separate cleaning step to remove potential dirt, grease and residues. This is done with a neutral detergent.

Contact time and kill rate

Choosing suitable products is only half the job. There are multiple factors than can determine the effectiveness of a cleaning and disinfection system – which are highlighted in this article.

It is essential to understand and follow the instructions printed on the labels of disinfectant products. It is also of utmost importance to achieve the required contact time. If after applying the disinfectant a surface dried up before the required contact time, it is unlikely that the kill rate will have been achieved as per manufacturer recommendation.

Contact time can sometimes be a challenge if it’s 10 to 15 minutes, especially in areas with high air changes. Chances are also that operators might spray and wipe without waiting long enough. This is why shorter contact times are easier to adhere to.

So-called “ready-to-use products” reduce the potential for operator errors. Concentrates require correct dilution, because a concentration that is too high can leave residues and increase cost, while overdilution will not achieve the required kill rate.

Whilst most disinfectants are tested at 20°C and the temperature in cleanrooms is usually quite stable, there are some concerns when it comes to cold stores in cleanrooms. This is not only due to higher humidity but also lower temperatures, which could necessitate longer contact times. Additional validation might also be required.

It is essential to understand and follow the instructions printed on the labels of disinfectant products

Training, suitable tools and types of surfaces

The combination of application equipment, operator and technique are essential factors in a successful cleaning and disinfection regime. Operators do require continuous training on cleanroom topics and the correct application of the relevant company SOPs.

Providing cleaning staff with suitable cleanroom cleaning tools, which meet the demands of the facility, is important to achieve the best possible results and to minimise operator errors and avoid taking short cuts. It is also important to review cleaning and disinfection SOPs to check for their practicality and ease of understanding. The provided tools, chemicals and cleaning techniques in the SOPs shouldn’t be a stumbling block to a successful cleaning and disinfection regime.

Other factors affecting the performance of a cleaning and disinfection system are the types of surfaces as well as shelf life. It’s obvious that expired products shouldn’t be used. Some companies tend to blend their own disinfectants to save costs but typically won’t go through the comprehensive product development cycle and testing of products. Those would include stability and efficacy testing, mode of action, material compatibility, residues etc. Comprehensive testing, change control and guaranteed quality as well as batch-specific certificates (COA – Certificate of Analysis, COI / COS certificate of irradiation / sterility) are part of the regulatory expectations.

Whilst from an end-user perspective the chance of cost saving seems easy, chances are that these can lead to regulatory findings or even worse, can cause a microbiological contamination in the cleanroom or final product. Product recalls and reputational damage outweigh the cost of using the right products suitable for the dedicated area. •

To achieve the best possible results in cleaning and disinfection, cleaning staff must be equipped with suitable cleanroom cleaning tools that meet the demands of the facility