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 digestive endoscopy using sterile devices, it appears necessary to put in place a process of endoscope reprocessing capable of ensuring the complete elimination 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 contaminated with suspensions of Pseudomonas aeruginosa, Aspergillus niger and Bacillus subtilis spores. Two procedures were then followed: (1) manual washing only, and (2) treatment in SS1 without prewashing. Recoveries of organisms were made from each channel according to a standard methodology to discover any survivors. Contamination controls we re assessed to measure the logarithmic reduction between the initial contamination and that recovered from the channels. Six cycles per micro-organisms, per type of endoscope, and per type of procedure were carried out. From an initial contamination leve l of 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. The maximum reduction with washing alone was by a factor of 10(3 +/- 0.1)for B. subtilis and the minimum reduction factor was 10(3 +/- 0.3)for P. aeruginosa. Considering the results obtained with SS1 without prewashing and the efficacy obtained from washing only, the washing step offers an additional antimicrobial assurance reduction factor of between 10 and 103.1. This study shows that SS1, integrated into an overall reprocessing procedure for digestive endoscopes, is capable of delivering the complete elimination of contaminating micro-organisms in a reduced time and eliminates the toxic risk of reprocessing associated with aldehyde based disinfectants.