Testing the Efficacy of Autoclaves

Testing the Efficacy of Autoclaves

Quality control is essential to ensure that potentially infectious agents are destroyed by adequate sterilisation regimes. There are a number of ways in which the efficacy of an autoclave may be tested. Browne's tubes are glass tubes that contain heat sensitive dyes. These change colour after sufficient time at the desired temperature. Bowie Dick tape is applied to articles being autoclaved. If the process has been satisfactory, dark brown stripes will appear across the tape. Pale brown stripes are suggestive of poor heat penetration, and an unsatisfactory sterilisation process. These methods give an immediate indication of the success or otherwise of an autoclave run but they are only suggestive of a successful sterilisation. Spore strips may be placed inside the autoclave at the start of its cycle. After running, the autoclave the strip is recovered and cultured. Absence of growth after a suitable period indicates a successful run. The problem with this method is that it is retrospective. If a problem has arisen, then this will be discovered only when the spores have germinated. This is probably too late to take effective action other than to call in an engineer to prevent further problems