Cleanroom Microbiology 101: Identifying & Controlling Sources of Contamination

Cleanroom Microbiology 101

Eliminating microbial contaminants is essential in a cleanroom environment. The risk associated with a contaminated cleanroom is overwhelming. Even the smallest level of contamination can lead to a variety of problems that can damage an organization’s reputation and result in numerous fines and fees. Product recalls and regulatory sanctions are just some of the possibilities when contamination is not controlled. In the most severe cases, a problem can lead to consumer illnesses and even death.

The most important thing to remember is that contaminated cleanrooms can lead to contaminated products. The result of contaminated products depends on the type of contamination, the use of the product, and how quickly the problem is discovered. A proper understanding and pro-active steps can keep these issues from occurring.

Cleanroom Microbiology

Keeping a cleanroom free of microbial contaminants begins with an understanding of cleanroom microbiology. We’ll cover several topics, including:

  • Cleanroom design
  • Personnel policies
  • Material transfer and flow protocols
  • Monitoring
  • Cleaning, sanitization, and disinfection

Eliminating microbial contaminants from a cleanroom environment is made more complicated by the nature of microorganisms. They are nearly everywhere, and they are remarkably resilient. They can exist in the harshest environments on earth, and they can lie dormant for years before becoming active again. They are also remarkably easy to spread.

The Human Element

Microorganisms become a severe risk to cleanrooms when mixed with another frequent visitor, humans. Microorganisms can be easily spread from one surface to another. All it takes is one touch of a contaminated surface, and contaminations can be quickly brought into the environment.

Contamination Sources

The first step in controlling microbiological contamination is understanding the possible sources. Since these contaminants can be found nearly anywhere and are so easily spread, the more we understand them, the better the likelihood we have of keeping them out of cleanroom environments.

Microorganisms can be categorized based on five factors:

1. Optimal Growth Temperature

Microorganisms have a wide range of optimal growth temperatures. Different types can thrive in temperatures below 15° C, while some are best suited for temperatures as high as 80° C. So, the cleanroom temperature impacts the type of microorganisms most likely to thrive.

2. Shape

Microorganisms come in a variety of shape classes, including round, rod-shaped, spiral, and vibrio.

3. Spore Production

Understanding spore production in microorganisms is essential. While not all types produce spores, those that do can cause an additional problem for keeping contaminants out. Spores can make bacteria more difficult to eliminate due to the fact that they allow the contaminant to survive even during massive fluctuations in their environment. Even procedures that destroy the microorganism itself may leave spores intact, leading to further contamination in the future.

4. Needed Atmosphere

Different microorganisms have different atmospheric requirements to survive. Understanding this part of biology is helpful in understanding what may be necessary to eliminate bacteria. The most common differentiator is aerobic vs. anaerobic. Aerobic microorganisms need oxygen to grow. Eliminating their source of oxygen would be one path to destroying the contaminant. Others are anaerobic, meaning they do not require oxygen to grow and could continue to thrive even with the elimination of oxygen. Unfortunately, it is not as simple as merely aerobic vs. anaerobic as various other microorganisms rely on other atmospheric conditions to grow and thrive.

5. Gram Stain Reaction

One of the most informative factors for categorizing microorganisms. Gram staining is a method of visualizing the structure of the bacteria’s outer cell wall. Most types fall into one of two groups, negative or positive.

Gram-Negative Cells

Most often found in relation to stagnant water or moisture in a cleanroom, gram-negative bacteria have a thin cell wall, surrounded by an outer membrane. They are often found in water systems, pipes, hoses, sinks, drains, and other areas frequently exposed to water. Gram-negative bacteria are especially dangerous as a contaminant because they are a source of endotoxins. Released when the cell is destroyed, it can lead to serious health issues in humans.

Gram-Positive Cells

This type of cell lacks an outer cell membrane and is the most common microorganism in cleanrooms. This is likely due to the fact that they are often found on the most common inhabitant on cleanrooms, humans. They can be carried on clothing, skin, and even hair. When gram-positive bacteria enter into a clean room, it is usually related to human error. The fact that some gram-positive microorganism can produce spores makes them even more challenging to eliminate.

Minimizing and Controlling Microbial Contamination

One of the most widely accepted practices for preventing the spread of contamination is known as the aseptic technique. Following this technique includes carefully following “first air” protocols and not allowing a disruption in the airflow from the filtrations source. It also includes strict adherence to rules regarding exposing sterile items to non-sterile items and using all appropriate sterile instruments and gloves.

Controlling and Enforcing Proper Cleanroom Procedures

An understanding of the biology of microorganism contamination must be paired with clear processes and protocols that are thoroughly communicated to personnel and consistently enforced.

Because humans are the most likely source of cleanroom contamination, all personnel should be properly trained and consistently reminded of the essential behaviors and processes. These include proper hygiene, good aseptic technique, working deliberately, always following processes, and having a good attitude toward proper procedures.

In addition to personnel matters, protocols must also be enforced related to other possible sources of contamination. These include quality control testing of raw materials, ongoing maintenance, cleaning and disinfection of cleanrooms and surrounding areas, proper cleanroom construction, maintenance of positive pressure and filtration system, and constant monitoring for contamination.

Resources and Documentation

Those seeking more information on identifying and controlling sources of contamination can find extensive documentation available through the Food and Drug Administration (FDA), the Parental Drug Association (PDA), the United States Pharmacopeia (USP), and the Code of Federal Regulations (CFR).