Currently available sporicides for use in healthcare, and their limitations

Clostridium difficile has been recognised for some time as a pathogen which can contaminate the environment and which is associated with secondary spread via this route. Unfortunately many of the disinfectants currently used in healthcare environments are inactive against this organism. For example, alcohol-containing hand rubs do not have sporicidal activity and some quaternary ammonium compounds and detergents may even encourage sporulation. European standards have been developed to allow a standardised methodology for testing the efficacy of disinfectants, but no European standard exists for testing products against C. difficile in medical environments. Most laboratories use an adapted version of EN 13704 which was designed for food, domestic and industrial applications. It is important when testing a disinfectant that it is tested under dirty as well as clean conditions and that the disinfectant is adequately neutralised. Some of the currently available biocides have good activity against C. difficile although relatively long contact times are sometimes required and this may not accurately reflect in-use practises. Other agents have very little activity against C. difficile even after a contact time of 1h. It has to be recognised that testing activity against C. difficile is technically very challenging and therefore there can be large interlaboratory variations in results. When interpreting data, it is essential to scrutinise the methodology used in detail.