Endoscopy supply water and final rinse testing: five years of experience

The penultimate stage in endoscope reprocessing is the final rinse with water following terminal disinfection. This requires a degree of microbiological and chemical control of the quality of the final rinse water.

To report experience gained over five years of testing, reporting and managing the quality of final rinse water for endoscopic devices.

Three endoscope reprocessing units, each comprising five endoscope washer-disinfectors (EWDs) supplied by two reverse osmosis (RO) water units, were subjected to weekly monitoring and control of final rinse water quality. EWDs were subjected to nightly thermal self-disinfection, and RO units were subjected to periodic sanitization with peracetic acid. Final rinse water samples were processed periodically for total viable counts (TVCs), Pseudomonas spp., endotoxins, conductivity, environmental mycobacteria and Legionella spp.

Over the five-year study period (2008-2013), no Pseudomonas spp., environmental mycobacteria or Legionella spp. were isolated from endoscopy rinse water. All conductivity readings were below 30 μs/cm. Endotoxin levels fluctuated over the recommended cut-off of 0.25 EU/mL, with no correlation with TVCs. Trend analysis of TVCs established alert and action limits. Apart from the supply water of one EWD becoming contaminated with Aspergillus spp., there have been no interruptions to operational capacity of the endoscope reprocessing units.

Quality control principles coupled with appropriate thermal and chemical disinfection of EWDs resulted in the achievement of microbiological standards for final rinse water. A co-ordinated team approach between the microbiology department, infection control department, endoscope unit managers and estates department is required to achieve this degree of success.