Risk of contamination of sterile biopsy forceps in disinfected endoscopes

Abstract

Background: Previous studies have shown that pathogens may persist within bacterial biofilms in endoscope accessory channels despite high-level disinfection. Breaching the gastrointestinal mucosa with biopsy forceps contaminated at time of passage has the potential to cause cross-infection between patients.

Methods: We studied contamination risk of sterilized biopsy forceps passed through endoscopes after high-level disinfection. For each trial, five video colonoscopes, duodenoscopes, and gastroscopes were used. All endoscopes had been previously processed and stored for 10 or more hours. Sterile biopsy forceps were inserted and retrieved followed by vortexing the tips in 15 mL of soy broth. Under a laminar flow hood, the broth was filtered through a 0.2 microm millipore membrane and plated. Because of minimal bacterial growth resulting from the above, soy broth (> 20 mL) was flushed through two video colonoscopes, duodenoscopes, and gastroscopes on two occasions and collected. The effluent was plated using a sample of 0.1 mL dilution. The remaining suspension was passed through a millipore filter, and the filter was cultured. All cultures were incubated more than 48 hours.

Results: Biopsy forceps underwent a total of 24 anaerobic and 75 aerobic cultures. Microbacterial growth occurred on 17 plates: 7 from gastroscopes, 5 from colonoscopes, and 5 from duodenoscopes. Fifteen plates grew staphylococcus for a total of 21 colonies, 1 plate grew 1 colony of propionibacter, 2 plates grew diphtheroids for a total of 4 colonies, and 1 plate grew a single colony of lactobacillus. Cultures from soy broth flushed through the various endoscopes grew on 5 plates: 3 from gastroscopes and 2 from duodenoscopes grew a total of 8 colonies of staphylococcus.

Conclusions: With proper cleaning technique, a 20-minute soak in 2% glutaraldehyde is effective in disinfecting endoscopes. Although current procedures for endoscope disinfection remain imperfect, we found that in this clinical setting, infection of pathogenic gastrointestinal flora is unlikely when using sterile biopsy forceps.