Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness

•Moisture may foster microbial growth and biofilm development in endoscopes.•Retained moisture was detected in 49% of endoscopes.•Microbial growth was found in samples from 71% of endoscopes.•Retained fluid was associated with higher ATP levels and microbial growth.•Improvements in reprocessing and drying methods are needed to ensure patient safety. Endoscopy-associated infection transmission is frequently linked to inadequate reprocessing. Residual organic material and moisture may foster biofilm development inside endoscopes. This study evaluated the effectiveness of endoscope drying and storage methods and assessed associations between retained moisture and contamination. Endoscope reprocessing, drying, and storage practices were assessed at 3 hospitals. Researchers performed visual examinations and tests to detect fluid and contamination on patient-ready endoscopes. Fluid was detected in 22 of 45 (49%) endoscopes. Prevalence of moisture varied significantly by site (5%; 83%; 85%; P