Dr Deirdre Collins1,2, Professor Thomas Riley1,2,3,4
1School of Pathology and Laboratory Medicine, University of Western Australia, Crawley, Australia
2School of Medical & Health Sciences, Edith Cowan University, Joondalup, Australia
3School of Veterinary & Life Sciences, Murdoch University, Murdoch, Australia
4Department of Microbiology, PathWest Laboratory Medicine, Nedlands, Australia
Clostridium difficile is the primary cause of nosocomial diarrhoeal disease. C. difficile spores are particularly resistant to disinfectants and frequently contaminate hospital equipment. Washer/Disinfectors (WDs) are commonly used to clean and decontaminate soiled equipment in health care facilities. This study aimed to evaluate the effectiveness of the DEKO-190 WD in removing C. difficile spores from contaminated bedpans.
Plastic carriers were inoculated with sterile human faeces containing ≥ 1×10⁷ CFU/ml C. difficile spores and taped to a sterile plastic bedpan. The bedpan and sterile negative controls were subjected to short, long or intensive wash cycles in the WD using one of two test detergents : Formula A (generic) and Formula B (highly alkaline). Residual spore counts were determined and mean log₁₀ reductions in spores were calculated for each wash cycle.
Mean log₁₀ reductions were 3.21(SEM ±0.20) and 2.82 (±0.13) for Formula A and B, respectively, for the short cycle, 3.65 (±0.44; Formula A) and 5.30 (±0.43; Formula B) for the long wash, and 3.37 (±0.58; Formula A) and 4.64 (±0.47; Formula B) for the intensive cycle. Residual spores were isolated from negative control carriers for every wash cycle.
In conclusion, washing with the DEKO-190 significantly reduced spore concentrations on carrier surfaces on a bedpan. However, the temperature inside the DEKO-190 was not sufficient to inactivate all spores, which exhibited high temperature resistance in other heat tests. Spore counts were most effectively reduced when carriers were washed on a long or intensive cycle using alkaline detergent.
Dr Deirdre Collins is a postdoctoral researcher at Edith Cowan University, working with Professor Thomas Riley’s Clostridium difficile research group. Her research focusses on the epidemiology of Clostridium difficile infection from a One Health perspective.