Microbiological testing services for cleanrooms according to international standards

Cleanrooms are tightly controlled environments concerning factors such as temperature, humidity, pressure, and particle levels, aimed at ensuring high-quality and safe products in industries such as pharmaceuticals, electronics, and food. Maintaining microbiological standards in cleanrooms plays a crucial role in preventing microbial contamination, protecting products, and ensuring worker health. Let’s explore with INTECH Service about cleanroom microbiological standards and methods of microbiological testing in the article below!

What are cleanroom microbiological standards?

Cleanroom microbiological standards are metrics for measuring the level of microbial contamination in air, surfaces, and materials/equipment within cleanrooms. These standards are defined by international organizations such as ISO, WHO, EU, FDA, and national regulations.

According to reference standards, cleanrooms are classified into cleanliness levels from ISO 1 to ISO 9, corresponding to the quantity of particles sized between 0.1 and 5 micrometers per cubic meter of air. However, these standards do not specifically address microorganisms; they serve as a reference for establishing cleanroom microbiological standards.

According to Appendix 6 of the Good Manufacturing Practice (GMP) guidelines from the World Health Organization (WHO), clean areas classified as levels A, B, C, D must all control the level of microbiological contamination during operations. The values in cleanroom microbiological standards are clarified in the following table:

Microbiological testing services for cleanrooms

Cleanroom microbiological standards are typically applied in industries involved in pharmaceuticals, cosmetics, food, and other sectors related to human health.

Why adhere to cleanroom microbiological standards?

Although cleanrooms are designed to control physical factors like temperature, humidity, pressure, and airborne particle levels, this does not guarantee that microorganisms cannot exist and thrive in this environment.

cleanroom microbiological control
Microorganisms, including bacteria, fungi, and viruses, can adhere to airborne particles and move with them within the cleanroom. Therefore, even with low dust concentrations in the cleanroom, there is still a possibility of microorganisms being present and causing contamination of products or impacting human health.

This is why researching and controlling the quantity of microorganisms in cleanrooms is extremely important. It helps promptly issue warnings and assess cleaning mechanisms and potential sources of infection when microbial levels in cleanrooms exceed regulated standards.

Common Methods for Microbiological Testing in cleanrooms

Surface Sampling Method

Remove a sterile swab from its package and moisten the tip by dipping it into a dilution fluid.

Swipe the swab over a defined area of approximately 20 – 100 cm² on the surface to be tested.

Cut off the swab’s handle in a sterile manner and place the swab back into the tube containing the initial solution.

surface sampling method for microbiological testing

Store the sample in a refrigerator at 1°C – 4°C and transport it to the testing facility ideally within the first 4 hours, but no later than 24 hours.

Perform microbiological testing as soon as possible; it should not exceed 24 hours. Dilute the solution in the tube with suitable compounds and process to obtain the initial inoculum.

Inoculate the initial inoculum onto culture plates and incubate at appropriate temperature and time conditions.

Count the number of colony-forming units (CFU) per milliliter of initial inoculum. Compare the results with the limits specified in cleanroom microbiological standards.

Settle Plate Method

The settle plate method, specified in cleanroom microbiological standards, determines the quantity of microorganisms to maintain cleanliness levels as required.

Nutrient agar plates are used in passive settle plate method. These plates are typically placed in room corners, near doors, and areas with high contamination risks.

It is mandatory to check for contamination before using the nutrient agar plates. Afterwards, place the plates in suitable positions for 30 minutes to 4 hours.

Plates should be placed under static air conditions. Larger particles tend to settle faster due to gravitational forces, while smaller particles are influenced by air currents.

Choose locations to place plates where airborne particles are most likely to be captured.

Method of placing agar plates for microbiological testing

After a maximum of 4 hours, cover the nutrient agar plates and incubate. The incubation period will vary. Bacteria are typically incubated at 37°C for 24 – 48 hours, while molds and yeasts are incubated at 25°C for 3 – 5 days.

Results from the nutrient agar plates are interpreted based on the number of colony-forming units (CFU) per hours the plates were placed.

International Standard cleanroom Microbiological Measurement Company

With an advanced, state-of-the-art measurement system and a team of experienced experts and engineers in the field, INTECH Service guarantees to provide accurate, reliable cleanroom microbiological measurement services at competitive prices and optimal quality. Contact us today for the earliest consultation.