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Henning Thomasen, Klaus-Peter Steuhl, Daniel Meller; Validation Of An Automated Test System For Sterility Controls Of Amniotic Membrane For Clinical Applications. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3546.
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Cryopreserved amniotic membrane (AM) is widely used in ophthalmology because of its beneficial clinical capabilities. For clinical use a careful testing for microbial contamination is essential to ensure a safe application. Up to now there has been no validated automated test system according to EU regulations to perform this task. In our study we evaluated the use of the BacT/Alert® test system for the screening of microbial growth in AM.
Sections of fresh AM which were cleaned of placental blood and tissue residues, cryopreserved AM (each about 5 cm2) were injected separately in BacT/Alert culture media test bottles. BacT/Alert i-AST® bottles were used to evaluate the growth of fungi and aerobic bacteria and BacT/Alert i-NST® bottles to evaluate anaerobic bacteria. Several bacterial and fungal test strains according to European Union regulations were applied to test the performance of the system (Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, Aspergillus brasiliensis, Propioniobacterium acnes and clostridium sporogenes). About 10 to 100 colony forming units of each germ were applied on the samples prior to injection in the corresponding test bottles. For each strain about four bottles with AM samples were inoculated, two additional battles only contained the germ to verify its growth while bottles with samples lacking germs served as negative controls. Bottles were incubated at 37°C for a period of seven days. In case of microbial growth within a test bottle the germ was subcultivated and identified.
Growth of the test strains was detected in all inoculated samples within the seven days incubation period. Neither non-processed nor cryopreserved AM inhibited the growth of the germs, despite the standardised application of antibiotics in cryopreserved AM.
Since all applied test strains were detected, we conclude that the BacT/Alert® system is suitable for testing of the microbial safety of amniotic membrane in clinical practice according to EU regulations.
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