Contamination of a purified water system by Aspergillus fumigatus in a new endoscopy reprocessing unit

Use of purified water for the final rinse stage of disinfected endoscopes is an important element of quality control. We describe the detection and management of Aspergillus fumigatus contamination of a new reverse osmosis unit supplying 10 automated endoscope reprocessor basins. Prompt detection and reaction to this contaminant were possible because of the introduction of a comprehensive program for microbiological monitoring of rinse waters, which included total viable counts, endotoxin, conductivity, and Pseudomonas spp.