Endoscope decontamination: a comparison of the Wolf 35100 and DSD-91 systems

The Wolf 35100 and DSD-91 endoscope disinfection machines were compared. Using a total viable count method, the degree of contamination of an Olympus GIFXQ20 endoscope was assessed following inoculation with a suspension of Pseudomonas aeruginosa and again following disinfection cycles in each machine, using 2% glutaraldehyde as the disinfectant. Both machines performed satisfactorily, with an average reduction of between 7 and 8 log10 cfu ml-1 P. aeruginosa following disinfection. The dilution effect on the glutaraldehyde of repeated disinfection cycles was also assessed for each machine. After 40 cycles in the DSD-91 and 25 cycles in the Wolf 35100 machines, the dilution of glutaraldehyde may give rise to concern, especially if adequate pre-cleaning of the endoscope is not carried out. The DSD-91 machine has certain advantages over the Wolf 35100 in terms of endoscope capacity, running costs and ease of maintenance. Both machines give similar results for endoscope disinfection.