Evaluation of the microbicidal efficacy of STERIS SYSTEM I for digestive endoscopes using GERMANDE and ASTM validation protocols

In the light of more and more invasive procedures being carried out in dige stive endoscopy using sterile devices, it appears necessary to put in place a process of endoscope reprocessing capable of ensuring the complete elimi nation of micro-organisms contaminating the device. We undertook a study of the microbial efficacy of STERIS SYSTEM 1 (SS1) which purports to achieve this objective. The channels of a gastroscope and a colonoscope were contam inated with suspensions of Pseudomonas aeruginosa, Aspergillus niger and Ba cillus subtilis spores. Two procedures were then followed: (1) manual washi ng only and (2) treatment in SS1 without prewashing. Recoveries of organism s were made from each channel according to a standard methodology to discov er any survivors. Contamination controls were assessed to measure the logar ithmic reduction between the initial contamination and that recovered from the channels. Six cycles per micro-organisms, per type of endoscope, and pe r type of procedure were carried out. From an initial contamination level o f 10(6) micro-organisms per endoscope, no micro-organisms were recovered in 35 of the 36 cycles with the SS1. In one cycle with the colonoscope, three B. subtilis organisms were recovered from the channels. Washing only gave microbial reductions which varied according to the micro-organism tested. T he maximum reduction with washing alone was by a factor of 10(3+/-0.3) for B. subtilis and the minimum reduction factor was 10(3+/-0.3) for P. aerugin osa. Considering the results obtained with SS1 without prewashing and the e fficacy obtained from washing only, the washing step offers an additional a ntimicrobial assurance reduction factor of between 10 and 103.1. This study shows that SS1, integrated into an overall reprocessing procedure for dige stive endoscopes, is capable of delivering the complete elimination of cont aminating micro-organisms in a reduced time and eliminates the toxic risk o f reprocessing associated with aldehyde based disinfectants. (C) 2001 The H ospital infection Society.