There are two main sources of contamination in cleanroom: particles and microorganisms, which can be caused by human and environmental factors, or related activities in the process. Despite best efforts, contamination will still penetrate into cleanroom. Specific common contamination carriers include human bodies (cells, hair), environmental factors such as dust, smoke, mist or equipment (laboratory equipment, cleaning equipment), and improper wiping techniques and cleaning methods.
The most common contamination carrier is people. Even with the most stringent clothing and the most stringent operating procedures, improperly trained operators are the biggest threat of contamination in cleanroom. Employees who do not follow the cleanroom guidelines are a high-risk factor. As long as one employee makes a mistake or forgets a step, it will lead to contamination of the entire cleanroom. The company can only ensure the cleanliness of the cleanroom by continuous monitoring and continuous updating of training with zero contamination rate.
Other major sources of contamination are tools and equipment. If a cart or a machine is only roughly wiped before entering cleanroom, it may bring in microorganisms. Often, workers are unaware that wheeled equipment rolls over contaminated surfaces as it is pushed into the cleanroom. Surfaces (including floors, walls, equipment, etc.) are routinely tested for viable counts using specially designed contact plates containing growth media such as Trypticase Soy Agar (TSA) and Sabouraud Dextrose Agar (SDA). TSA is a growth medium designed for bacteria, and SDA is a growth medium designed for molds and yeasts. TSA and SDA are typically incubated at different temperatures, with TSA exposed to temperatures in the 30-35˚C range, which is the optimal growth temperature for most bacteria. The 20-25˚C range is optimal for most mold and yeast species.
Airflow was once a common cause of contamination, but today’s cleanroom HVAC systems have virtually eliminated air contamination. The air in cleanroom is controlled and monitored regularly (e.g., daily, weekly, quarterly) for particle counts, viable counts, temperature, and humidity. HEPA filters are used to control the particle count in the air and have the ability to filter out particles down to 0.2µm. These filters are usually kept running continuously at a calibrated flow rate to maintain the air quality in the room. Humidity is usually kept at a low level to prevent the proliferation of microorganisms such as bacteria and mold that prefer humid environments.
In fact, the highest level and most common source of contamination in cleanroom is the operator.
The sources and entry routes of contamination do not vary significantly from industry to industry, but there are differences between industries in terms of tolerable and intolerable levels of contamination. For example, manufacturers of ingestible tablets do not need to maintain the same level of cleanliness as manufacturers of injectable agents that are directly introduced into the human body.
Pharmaceutical manufacturers have a lower tolerance for microbial contamination than high-tech electronic manufacturers. Semiconductor manufacturers that produce microscopic products cannot accept any particulate contamination to ensure the functionality of the product. Therefore, these companies are only concerned about the sterility of the product to be implanted in the human body and the functionality of the chip or mobile phone. They are relatively less concerned about mold, fungus or other forms of microbial contamination in cleanroom. On the other hand, pharmaceutical companies are concerned about all living and dead sources of contamination.
The pharmaceutical industry is regulated by FDA and must strictly follow Good Manufacturing Practices (GMP) regulations because the consequences of contamination in pharmaceutical industry are very harmful. Not only do drug manufacturers have to ensure that their products are free of bacteria, they are also required to have documentation and tracking of everything. A high-tech equipment company can ship a laptop or TV as long as it passes its internal audit. But it is not that simple for the pharmaceutical industry, which is why it is crucial for a company to have, use and document cleanroom operating procedures. Due to cost considerations, many companies hire external professional cleaning services to perform cleaning services.
A comprehensive cleanroom environmental testing program should include visible and invisible airborne particles. Although there is no requirement that all contaminants in these controlled environments be identified by microorganisms. The environmental control program should include an appropriate level of bacterial identification of sample extractions. There are many bacterial identification methods currently available.
The first step in bacterial identification, especially when it comes to cleanroom isolation, is the Gram stain method, as it can provide interpretive clues to the source of microbial contamination. If the microbial isolation and identification shows Gram-positive cocci, the contamination may have come from humans. If the microbial isolation and identification shows Gram-positive rods, the contamination may have come from dust or disinfectant-resistant strains. If the microbial isolation and identification shows Gram-negative rods, the source of contamination may have come from water or any wet surface.
Microbial identification in pharmaceutical cleanroom is very necessary because it is related to many aspects of quality assurance, such as bioassays in manufacturing environments; bacterial identification testing of end products; unnamed organisms in sterile products and water; quality control of fermentation storage technology in the biotechnology industry; and microbial testing verification during validation. FDA's method of confirming that bacteria can survive in a specific environment will become more and more common. When microbial contamination levels exceed the specified level or sterility test results indicate contamination, it is necessary to verify the effectiveness of cleaning and disinfection agents and eliminate the identification of contamination sources.
There are two methods for monitoring cleanroom environmental surfaces:
1. Contact plates
These special culture dishes contain sterile growth medium, which is prepared to be higher than the edge of the dish. The contact plate cover covers the surface to be sampled, and any microorganisms visible on the surface will adhere to the agar surface and incubate. This technique can show the number of microorganisms visible on a surface.
2. Swab Method
This is sterile and stored in a suitable sterile liquid. The swab is applied to the test surface and the microorganism is identified by recovering the swab in the medium. Swabs are often used on uneven surfaces or in areas that are difficult to sample with a contact plate. Swab sampling is more of a qualitative test.
Post time: Oct-21-2024