O066: Thermal disinfection of bedpans: European ISO 15883-3 guideline requirements are insufficient to ensure elimination of ARE and OXA-48 outbreak-strains

During 2012, our hospital was faced with a vancomycin-resistant Enterococcus faecium (VRE) outbreak. Washer-disinfectors are used for the cleaning and thermal disinfection of bedpans. The European guideline NEN-ISO 15883-3 (ISO) states that washer- disinfectors have to achieve a minimum A₀ value of 60 for appropriate disinfection of bedpans (≈ 80 °C for 60 seconds or 90 °C for 6 seconds). However, previous data have shown that some E. faecium strains survive 60 seconds at 80 °C. Following ISO, the A₀ measurement should include a cold (a minimum interval of 60 minutes since the machine was last used) and hot start.

We determining the A₀ value of the VRE outbreak-strain and the outbreak-strain of the OXA-48 K.pneumoniae outbreak in another Dutch hospital during 2011. Moreover the impact of a cold start measurement on the A₀ value was evaluated.

The minimum A₀ value that results in the killing of all isolates was determined for both strains. Bacterial suspensions were heated at 65, 75 and 80 °C and samples for viable counts were obtained after 1,2,3 and 10 minutes at each temperature. VRE PCR and cultures were performed on bedpan swabs after disinfection; hot and cold start measurements were compared.

Adequate killing required a minimum A₀ value of 180 for the VRE outbreak strain and 120 for the OXA-48 K.pneumoniae. The cold start resulted in a 30% lower A₀ value, than the hot start. All washer-disinfectors in our hospital functioned in agreement with the European guideline, although the lowest A₀ value was 73, only just above 60. Swabs taken from bedpans processed in these washers with low A₀ values , were VRE-positive by PCR and cultures.

Both outbreak strains survived the A₀ value of 60 required in the ISO. VRE were identified by PCR as well as cultures of bedpans that had been disinfected by these washer-disinfector. We suggest to increase the minimal acceptable A₀ value of washer-disinfectors to at least 180. Furthermore, the cold-start is needed for adequate A₀-value measurement.

None declared.

Affiliations

1. Medical Microbiology and Infectious Diseases, Canisius Wilhelmina Hospital Nijmegen, The Netherlands

   • LB van der Velden
   • , MH Nabuurs-Franssen
   • , A van Leeuwen
   • , M Isken
   •  & A Voss

2. Medical Microbiology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands

   • LB van der Velden
   •  & A Voss

Corresponding author

Correspondence to LB van der Velden.

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