Bioburden Recovery Validation – Repetitive

Repetitive Bioburden Recovery Efficiency ensures that the method thoroughly extracts natural bioburden from the product. The repetitive method is used when the level of naturally occurring product bioburden is high. The extraction method involves multiple extractions from the same product until the number of Colony Forming Units (CFU) decreases significantly. The method must be validated before the routine bioburden testing. Due to the inherent limitations of the test procedure, 100 % recovery from the test product is not possible. The repetitive method produces less consistent results between replicates due to variable natural bioburden, is labor-intensive due to multiple extractions, and therefore is more expensive and complex than the inoculation method.
Repetitive recovery efficiency testing will result in a correction factor to be used to adjust the bioburden test results.

Why This Testing is Performed

Repetitive recovery is performed when the estimated bioburden on the product is high or to determine the natural bioburden on the product. The method involves performing multiple bioburden tests on the same product. After each repetition, the eluent is totally recovered from the product or product portion and enumerated. Results accumulated from the consecutive recoveries are compared.  This validation confirms that the bioburden testing method can consistently recover microorganisms from a product.

Have you tried our Test Navigator Tool? Try it now

Steps in Conducting This Test

1. Repetitive Extraction: Perform multiple extractions using the same method.
2. Enumeration: Enumerate all plates from each test and document the number of CFU.
3. Cumulative Analysis: Sum all CFU from all extractions to determine total recovery.
4. Efficiency Calculation: Recovery efficiency is calculated by comparing the number of CFU recovered from the first extraction to the total number of CFU recovered from all extractions.
5. Correction Factor: The Correction factor is calculated based on the percentage recovery from the initial extraction.

Standards, Guidance, and Regulations

• ISO 11737-1: Specifies methods for determining bioburden on medical devices.