10/4/2011
by Sara Toole, Microbiology Department Manager, B.S. RM(NRCM) CQA (ASQ)
Tissue banks provide a great service for those in need. But, just like pharmaceuticals and medical devices, donated tissue needs to be rendered safe before it can be used on patients. The American Association of Tissue Banks (AATB) and the Food and Drug Administration (FDA) set the standards for procurement, processing and distribution of tissue. For skin donations, the tissue must meet criteria as determined by the AATB to be considered acceptable.
There are specific microorganisms which are not permitted to be present on skin tissue products, and there are tests which are used to determine their presence. A difficulty arises, especially with tissue samples, when you have a high quantity of microorganisms on a sample. Skin, by nature, is not sterile and has microorganisms on the surface. Determination of which microorganisms are present on the skin is critical and it often performed using a sterility test. The sterility test provides an environment which allows many types of microorganisms to grow. This would include microorganisms that might be considered acceptable for the skin, as well as those that are objectionable. To ensure proper identification of the microorganisms which are found in the sterility test it is essential to have a validated identification system, operated by specifically trained personnel. Nelson Laboratories has both MicroSeq® 16S rDNA Bacterial Identification System and Vitek® 2 Compact available. A new test method for determining skin suitability has been pioneered by Nelson Laboratories. The test provides specific growth conditions for the objectionable microorganisms which provide better detection and sensitivity. This selective process specifically detects the microorganisms that AATB has determined cannot be on the skin products.
Validation of this test is performed by inoculating skin samples with the objectionable microorganisms which will be tested for, to ensure they can grow in the test system. Once validated, the test is conducted on the actual skin samples for product release. If none of the specified microorganisms are detected, then the tissue is released for distribution.
Medical devices and pharmaceutical products may be pooled together in batches for testing; however, tissue testing must be performed on each individual donor. Special care must be taken to identify the most effective testing for donor tissue, allowing tissue banks to ensure patient safety while honoring the gift of donation.