20.03.2014 – Sterility Testing – 2nd isolator placed into service
After what has been several months of comprehensive qualification, we were able to release our 2nd isolator for sterility testing in March 2014 and place it into service.
The construction of the 2nd isolator is identical to that of our isolator that has been operating reliably for 9 years, and it was built by the company Ehret according to our specific requirements.
The isolator is a 4-glove stainless steel isolator (rigid wall isolator) with turbulent air flow, which can be sterilised with hydrogen peroxide gas. The isolator is operated by so-called batch operation (load, sterilise, test, unload, clean, load…). Loading and unloading occurs via the front glass, which can be opened. Testing within the isolator itself is performed exclusively by operator intervention by means of the isolator’s sleeves and gloves
The hydrogen peroxide gas required for sterilisation is produced by two external gassing units driven by the isolator. The hydrogen peroxide gas produced on an evaporator plate is directly introduced into the isolator work space by a tubing and piping system, distributed by fans and returned to the VHP generator via a second pipe, whilst a defined amount of hydrogen peroxide is continually replenished each minute during the entire sterilisation time. Drying, conditioning and sterilisation are performed via the gassing units. The aeration that follows the sterilisation is performed independently of the gassing units with sterile air, by sterile filtering air from the surrounding room via a prefilter and then through the supply air HEPA filter by the isolator. The air, which is still enriched with hydrogen peroxide, is conducted outside by a piping system via the exhaust air HEPA filter until a residual gas concentration is reached, which does not influence the subsequent testing negatively. The isolator then enters into sterile routine operation and the testing can commence under turbulent airflow at 100 Pascal overpressure.
The isolator is equipped with a hose pump integrated into the working surface for performance of sterility testing by membrane filtration and with fixtures for storage of the materials required for sterility testing.
The efficacy and distribution of hydrogen peroxide gassing was demonstrated in numerous qualification experiments with biological and chemical indicators. The routinely used gassing cycle guarantees a sterility assurance level of 10-3 at over 25 tested measuring positions with a defined worst-case load.
A negative effect of H2O2 gassing on testing materials and test samples during and after gassing could subsequently be ruled out by numerous additional microbiological qualification experiments.
With this 2nd isolator, BioChem GmbH now has a safe internal back-up system, thus ensuring even more reliable processing of your often time-critical samples for sterility testing.
Our 17-year experience with isolator technology has shown that the secondary contamination rate and the rate of false-positive results can be markedly minimised with the use of isolator technology due to the strict separation between the testing and the operator performing the test, in addition to the standardised decontamination of surfaces.
The isolator provides a safe environment for sterility testing that meets the requirements.
Dr. Wolfgang Leis Dr. Jürgen Branke
Division Director, Microbiology Technical Director