Clostridium difficile is not reliably eradicated by ward bedpan washers unless alkaline detergent is used

Abstract number: O467

Alfa M., Olson N., Beulow-Smith L.

Objective: The objective of this study was to use simulated-use testing to evaluate the efficacy of C. difficile spore elimination by W-BPW compared to Central Processing Dept. washers (CPD-BPW).

Methods:C. difficile spores were suspended in sterile faeces to give ~10E6 cfu/mL and 0.1 mL of this preparation was spread over a defined surface area of the bedpan and allowed to dry 2.5 Hrs or overnight at room temperature. The inoculated bedpans were processed using the W-BPW or the CPD-BPW. Rodac plates containing CDMN media were used to detect residual C. difficile sporeson processed bedpans. In addition the faecal-spore suspension was placed in a sealed vial and processed through the BPWs to determine if the thermal conditions (no wash off effect) were sufficient to kill the spores. An unprocessed control was compared to the processed sample in the sealed vial to determine the Log10 reduction in spores due to thermal exposure. The ability of thermal conditions to kill C. difficile spores in PBS (i.e. no organic challenge) was also evaluated using spore suspension testing at 80oC and 90oC. Two different makes of W-BPWs were evaluated.

Results: Our data on suspension testing showed that the C. difficile spore count was not reduced after 5 minutes at 90oC. Simulated-use testing demonstrated that the ward-BPW when used without detergent, did not effectively eliminate C. difficile spores from inoculated plastic or stainless steel bedpans whereas the CPD-BPW did. The thermal disinfection default cycle in the two makes of W-BPW and the CPD-BPW was 80°C for 1 minute. The ISO15883–3 guidance document recommends these thermal conditions as adequate for reprocessing of bedpans. Exposure to these conditions resulted in ~1 Log10 reduction in spores. However, the 80oC for 1 min thermal cycle combined with the 116°C drying cycle for 7 mins used by the CPD-BPW killed 6 Log10 C. difficile spores. Further testing showed that using an alkaline detergent along with the W-BPW did reliably eliminate C. difficile spores.

Conclusion: Despite the wide use of 80°C for 1 minute, our data showed that these thermal conditions alone were not effective in killing C. difficile spores. Only when alkaline detergent was used was the W-BPW able to eliminate C. difficile spores from bedpans. We recommend that alkalkine detergent always be used with W-BPWs to reduce the risk of C. difficile spores remaining on reprocessed bedpans as this could pose a risk for nosocomial transmission.