This invention relates to a test device and method, in particular to a device and method for testing the biocidal efficacy of a liquid sterilant.
The efficacy of sterilization processes is generally assessed by the use of biological indicators; these consist of a known number of micro-organisms, established as having a high resistance to the particular process, attached to or suspended on an inert carrier. For most sterilization processes, the use of bacterial spores inoculated onto a paper disc carrier is sufficient.
When dealing with liquid sterilants, however, there is a danger of release of the bacterial spores into the sterilization fluid medium. A conventional carrier is therefore inappropriate due to a likelihood of contamination of the sterilization fluid.
There has now been devised a test device and method which overcomes or substantially mitigates the problems associated with conventional methods of testing liquid sterilants.
According to the invention, a test device for assessing the biocidal efficacy of a liquid comprises a vessel, means for introducing a predetermined volume of the liquid into the vessel via an inlet, and a porous filter interposed between the inlet and the vessel, wherein the vessel contains a predetermined quantity of biologically active organisms and the filter has a pore size effective to retain said organisms.
According to another aspect of the invention, a method for assessing the biocidal efficacy of a liquid comprises
a) providing a vessel in communication with an inlet and containing a known quantity of biologically active organisms, the inlet being separated from the vessel by a porous filter having a pore size effective to retain said organisms,
b) introducing a predetermined volume of the liquid into the vessel via the inlet,
c) removing the liquid from the vessel via the inlet or via an outlet with a similarly effective filter,
d) introducing a culture medium for the biologically active organisms into the vessel, and
e) ascertaining whether growth of biologically active organisms takes place in the culture medium.
The device and method of the invention are advantageous primarily in that they enable testing of the biocidal activity of a liquid without the risk of contamination of the liquid with organisms utilised in the test procedure.