Cleanroom Decontamination: Application of Hydrogen Peroxide Vapor Following Maintenance Activities

Although it is more commonly used to decontaminate separative devices such as isolators, vaporized hydrogen peroxide (VHP) also can be applied in cleanrooms to help mitigate control measure weaknesses, to support manual cleaning and disinfection efforts, and to reduce the likelihood of microbial contamination remaining after atypical activities occur. The latter include cleanroom-equipment maintenance operations that can require opening of panels for engineering access.

 

Panels are the access ports for machinery. Behind them are conduit areas containing wiring, sensors, and controls. Such areas are not part of the cleanroom space, so they are not subject to routine cleaning and disinfection. Thus, they can become niches for organisms (e.g., spore-forming microbes) that are adept at surviving for prolonged periods in inhospitable environments. Introduction of endospores poses challenges to a cleanroom space, making decontamination more difficult to achieve using conventional manual methods (e.g., wiping) — and thus calling for the use of sporicidal disinfectants.

 

Sandle, T. (2025) Cleanroom Decontamination: Application of Hydrogen Peroxide Vapor Following Maintenance Activities, BioProcess International, 23 (5): 30-34: https://www.bioprocessintl.com/facility-design-engineering/cleanroom-decontamination-application-of-hydrogen-peroxide-vapor-following-maintenance-activities 

 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

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The evolution of quaternary ammonium compounds

Quaternary ammonium compounds are surfactants composed of positively charged polyatomic ions. A longstanding example is benzalkonium chloride. Later generations of QACs achieve synergies through the incorporation of other chemicals designed to enhance their efficacy. This class of disinfectant has a broad-spectrum antimicrobial activity. The antimicrobial action of quaternary ammonium compounds involves perturbation of cytoplasm and the lipid bilayers that form the bacterial cell membrane.

 

This article looks at the efficacy of quaternary ammonium compounds and compares the performance of this class of biocides with comparable disinfectants and sets out why the latest generation of QACs represent an advancement. The article follows on from an earlier article published in The Clinical Services Journal (‘Advantages of quaternary ammonium compounds’) which considered the application of QACs as part of the infection control programme.

 

Sandle, T. (2025) The evolution of quaternary ammonium compounds, Clinical Services Journal, 24 (6): 41-45 https://www.clinicalservicesjournal.com/story/48469/the-evolution-of-quaternary-ammonium-compounds

 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

 

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Glove disinfection and aseptic technique: Creating a schema for the cleanroom and laboratory

 

There are different elements that contribute to good aseptic technique within the cleanroom and the laboratory. One such element is the donning of gloves, handling items appropriately, and keeping gloves regularly disinfected. Glove disinfection is an essential step for bacteriological control, although how successful control is maintained is dependent upon the type of disinfectant (these are generally alcohols for gloved hands), frequency of application, volume of disinfectant, application technique and the contact time. Other variables include purchasing gloves of a suitable material and design, and appropriate training. Aa an added control with more critical areas, the gloves are pre sterilised before donning (often purchased sterile by radiation or ethylene oxide).

As with other types of disinfection, the aim is not ‘sterilisation’ but to bring any bacterial density present on the gloves down to a level that is as low as possible (what is sometimes referred to as the "irreducible minimum"). Assessment, when required, is commonly through the use of agar contact plates onto the fingertips of each gloved hand (four fingers and the thumb) to create the ‘finger plate’ or ‘finger dab’. To avoid false negatives, the agar needs to be formulated with an appropriate disinfectant neutraliser.  

For cleanroom and laboratory managers seeking to maximise the maintenance of asepsis, glove control is an important element. This should take the form of a good practice schema and for this to be transitioned into a training module, supported by regular prompts in practice.  

In terms of what such a schema should look like, this article appraises the research that underpins an appropriate glove ‘sanitisation’ schema. This includes the central concerns of when and how effective glove disinfection is to be achieved. The key findings are that a 30 second disinfection time is suitable for both cleanroom and laboratory operations, provided a suitable technique is deployed and an alcohol-based disinfectant used. However, controls need to be in place to avoid the over disinfection of gloves since repeated applications increase the likelihood of microperforations occurring and thereby effective glove disinfection needs to be supported by a regular glove change procedure.  

Sandle, T. Glove disinfection and aseptic technique: Creating a schema for the cleanroom and laboratory, European Journal of Parenteral and Pharmaceutical Sciences, 28 (2): https://doi.org/10.37521/ejpps.28201
 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

Will ethanol be banned in Europe as the active ingredient for hand disinfectants?

Image by Tim Sandle

With ethanol be banned in the EU as the basis for hand disinfection? Do epidemiological studies confirm an increased risk for cancer from ethanol in exposed individuals? Why is the EU considering this move now?

I've noticed this report from Chemistry World:

Medical experts and health organisations from around the world have expressed concern over what they say would be a ‘misclassification’ of ethanol as a reprotoxic substance when it appears in biocidal products such as hand gels. They say there is no scientific evidence for the reclassification, which would result in significant risks to public health and safety if vital disinfectants were unavailable.

Disinfectant hand gels containing ethanol might no longer be available if the compound is reclassified as toxic to reproduction

The EU’s evaluation of ethanol’s use in products such as hand gels and disinfectants under the Biocidal Products Regulation (BPR) was assigned to Greek authorities back in 2007. In March, they submitted their draft report to the European Chemicals Agency (Echa) proposing that ethanol should be listed as a reprotoxic category 2 active substance (category 1 is the highest classification). This means it is a suspected human reproductive toxicant and follows some evidence of an adverse effect on sexual function and fertility, or on development. If ethanol was reclassified as a category 2, then biocides containing more than 3% would have to be labelled as reprotoxic. Effective hand-sanitising gels contain at least 60% alcohol.

Echa’s Biocidal Products Committee (BPC) is reviewing the report. Hanna-Kaisa Torkkeli, an Echa spokesperson, says it’s too early to predict the outcome, but expects an ‘opinion’ at the end of 2024 or, more likely, in 2025. The European Commission will make a final recommendation based on the BPC’s opinion.

To read the full article, see Chemistry World. 

In relation to this topic, this research paper, from 2024, concludes "There is no epidemiological evidence of toxicity for workers handling ethanol-containing products in industry or using EBHR in healthcare settings." EBHR = ethanol-based hand rubs.

Also see:  "Medical associations and expert committees urge that ethanol be approved as a virucidal active substance for use in hand antiseptics under the European Biocidal Products Regulation, without a CMR classification".

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

Chemical control: Chlorine and the disinfection of water

 

Heat or different biocidal products can be used to reduce microbial contamination in water. This includes strong oxidizing agents like chlorine dioxide and ozone. Historically, the introduction of chlorination to municipal water supplies led to a reduction in cholera and Salmonella (a process regularly in place, for the first time, in England from 1905) (1).

Chlorination can be applied to mains water and initial stages of water generation, for pharmaceuticals; however, it is generally not used thereafter with the preferred methods being ozone or heat. Chlorination is an important step for ensuring public drinking water and shared services, like swimming pools, remain suitable for human use.

This week’s article looks specifically at chlorine and its use as an antimicrobial agent in a water system. 

See:  https://www.linkedin.com/pulse/chemical-control-chlorine-disinfection-water-tim-cibhe/?trackingId=63gnZL34S0GL3HpIRZ2EeQ%3D%3D 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

Cleaning, disinfection and the contamination control strategy

 

 Enjoy the video!

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)

Disinfectant efficacy: Getting the temperature right

 Apart from a few exceptions, disinfection processes are considerably slower at low temperatures than at higher temperatures. This carries consequences for the use of disinfectants, especially in cold rooms where ‘cold-loving’ microbes present a contamination risk. To address this, either concentrations or contact times need to be increased, or an alternative disinfectant agent used. In this article, we take a look at the science.

Read the article for fre online:

Sandle, T. Disinfectant efficacy: Getting the temperature right, RRSL Life Sciences Series, 20^th March 2023 at: https://www.rssl.com/insights/life-science-pharmaceuticals/disinfectant-efficacy-getting-the-temperature-right/

 

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)