Effect of drying time, ambient temperature and pre-soaks on prion-infected tissue contamination levels on surgical stainless steel: concerns over prolonged transportation of instruments from theatre to central sterile service departments

SummaryIatrogenic transmission of prions through use of surgical instruments has been shown both experimentally and clinically. In addition, recent discoveries of prion protein accumulation in peripheral tissues such as appendix and muscle, and evidence suggesting human-to-human blood-borne transmission, have led to a concern that any residual soiling containing this agent may remain infectious even after sterile service processing. Removal of all proteinaceous material from surgical devices is extremely important for effective sterilization. This removal can be severely hampered if the contaminant is allowed to dry onto the instrument surface for any length of time. The current move to centralize sterile service centres and the inevitable lengthening of transport time between theatres and re-processing makes it necessary to minimize the amount of residual soiling adhering to an instrument before sterilization. This investigation simulates the period between the application of surgical instruments in theatre and their initial pre-wash by a washer/disinfector. The aim was to investigate the kinetics of drying at different temperatures, and the application of different commercially available pre-soak solutions in situ. The findings show that all pre-soaks significantly reduce (by up to 96%) the prion-infected tissue contamination, and that controlling the temperature whilst in transit between theatres and cleaning facilities may allow an increase in time before high protein adsorption levels occur.