Surfactant influence on rivulet droplet flow in minitubes and capillaries and its downstream evolution

Significant increased bacterial contamination with endoscope overnight and weekend storage times

BACKGROUND AND AIM

Forced-air drying (FAD) cabinets are recommended for storage of reprocessed endoscopes, but financial constraints prevent their universal application. The study aimed to determine bacterial contamination in flexible gastroscopes (FG) channels after storage, in a cabinet with filtered air and UV lights, but without FAD.

METHODS

Eight FG in clinical use in an endoscopy service of a large Brazilian hospital were sampled: immediately "Time zero" (N = 50), 12 h "Time 1" (N = 25), and 60 h "Time 2" (N = 25) after reprocessing. Following a flush-brush-flush of channels, 40-mL sterile water and 3 cm of the brush were collected. Each sample was divided, filtered onto two 0.22-μm membranes, and incubated in media without or with disinfectant neutralizer. Automated method was used for identification and antibiotic resistance test of isolated bacteria.

RESULTS

Bacterial contamination in times "1" and "2" was 5.9 and 16.1 times greater than that of "Time zero," respectively. Number of positive cultures in media with and without neutralizer was similar at times "1" and "2," while media with neutralizer produced more positive cultures at "Time zero." Most bacteria isolated at "Time 2" were Gram-negative rods (52.3%) and showed resistance to one or more antibiotics (65%).

CONCLUSION

Bacterial contamination was detected on reprocessed FG stored in non-FAD cabinets overnight (12 h) and increased with longer storage time (60 h). The contamination source is likely to be bacteria in biofilm which multiply in the absence of FAD. Evidence-based criteria should be available for storage time according to the cabinet available.

Turbulent fluid flow is a novel closed-system sample extraction method for flexible endoscope channels of various inner diameters

OVERVIEW

Effective sample extraction from endoscope channels is crucial for monitoring manual cleaning adequacy as well as for ensuring optimal sensitivity for culture after disinfection. The objective of this study was to compare the efficacy of Turbulent Fluid Flow (TFF) to Flush (F) or Flush-Brush-Flush (FBF) methods.

MATERIALS & METHODS

Pseudomonas aeruginosa and Enterococcus faecalis in artificial test soil-2015 (ATS2015) were used as bacterial markers while protein and carbohydrate were the organic markers for biofilm formed inside 3.2-mm and 1.37-mm polytetrafluoroethylene (PTFE) channels. TFF was generated using compressed air and sterile water to provide friction for sample extraction. Extraction for biofilm coated PTFE channels as well as for colonoscope channels perfused with ATS2015 containing 10⁸ CFU/mL P. aeruginosa, E. faecalis and Candida albicans was determined using TFF compared to FBF and F.

RESULTS

The extraction ratio for P. aeruginosa and E. faecalis from biofilm extracted by TFF compared to the positive control was significantly better than F for 1.37-mm channels (≥0.94 for both bacteria by TFF versus 0.69 to 0.72 by F for P. aeruginosa and E. faecalis, respectively) but not significantly different between TFF and FBF for 3.2-mm channels. F was also ineffective for extraction of protein and carbohydrate from 1.37-mm channels. Extraction efficacy by TFF from inoculated colonoscope channels was >98% for all test markers.

CONCLUSIONS

The novel TFF method for extraction of samples from colonoscope channels is a more effective method than the existing FBF and F methods.