Bacteriostasis/Fungistasis

Bacteriostasis/fungistasis testing evaluates a medical device’s ability to inhibit the growth of bacteria and fungi. This test is crucial for determining the sterilization process’ effectiveness and ensuring that the device is safe for patient use.  The test is designed to ensure that any residual inhibitory substance present in the test product does not impact the sterility test results.

Why This Testing is Performed

This test ensures the validity of a sterility test. It confirms that the test product does not contain any inhibitory substances and allows the detection of viable microorganisms during a sterility test. The test is performed on all new products or if there are any significant changes in the existing product’s manufacturing process or material. It is referred to as a method suitability test and is performed per regulatory standards prior to a sterility test.

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Steps in Conducting This Test

• Preparation: Select representative microorganisms (bacteria and fungi) relevant to the device’s intended use.
• Inoculation: Apply a known concentration of microorganisms to the device or its surface.
• Incubation: Incubate the device under controlled conditions to allow for microbial growth.
• Assessment: Evaluate the growth of microorganisms on and around the device.
• Interpretation: Determine the bacteriostatic/fungistatic properties by comparing the growth with control samples.

Standards, Guidance, and Regulations

When conducting bacteriostasis/fungistasis testing, it is essential to follow standards and guidelines to ensure accurate and consistent results. Key standards and regulations include:

• ISO 11737-2: Sterilization of medical devices Microbiological methods – Provides guidelines for sterility testing of medical devices, including requirements for bacteriostasis and fungistasis testing.
• USP <71>: Sterility Tests – Provides guidelines for sterility testing of pharmaceutical products, including bacteriostasis and fungistasis testing requirements.
• FDA Guidance: The U.S. Food and Drug Administration provides specific guidance on sterility testing for medical devices to ensure compliance with regulatory requirements.