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High-level disinfection of gastrointestinal endoscopes: are current guidelines adequate?
B J Kovacs1, Y K Chen, J D Kettering
1Department of Microbiology, Loma Linda University Medical Center, California 92350, USA.
Objective:
For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a 6-log reduction of mycobacterial inoculum under worst case conditions. The purpose of this study was to assess the adequacy of current guidelines for high level disinfection of GI endoscopes using alkaline glutaraldehyde in simulated-use testing.
Methods:
Various gastrointestinal endoscopes were contaminated with Mycobacterium chelonae in 46 experiments. Quantitative cultures were obtained from each endoscope channel separately after each step: inoculation, standardized manual cleaning, immersion in 2% glutaraldehyde (Cidex) for 10, 20, or 45 min at room temperature, 70% isopropanol rinse, and drying.
Results:
Manual cleaning alone achieved a 4-log reduction. After 10 min of glutaraldehyde exposure, but before alcohol rinse, two of 10 experiments failed to achieve a 6-log reduction. However, after alcohol rinse, all 10 experiments achieved HLD. After 20 min of glutaraldehyde exposure, but before alcohol rinse, one of 18 experiments failed to achieve a 6-log reduction. After alcohol rinse, all 18 experiments achieved HLD. After 45 min of glutaraldehyde exposure, but before alcohol rinse, one of 18 experiments failed to achieve a 6-log reduction. After alcohol rinse, all 18 experiments achieved HLD. Thus, if the entire reprocessing protocol including manual cleaning, glutaraldehyde exposure, alcohol rinse, and drying was taken into account, the required 6-log reduction of mycobacteria was achieved with a minimum of 10 min of glutaraldehyde exposure at room temperature.
Conclusions:
Current guidelines for high level disinfection using glutaraldehyde are appropriate. Alcohol rinse is a valuable adjunctive step for drying and for its bactericidal effects.
Insights
High-level disinfection (HLD) of GI endoscopes using alkaline glutaraldehyde meets FDA requirements. Even 10 minutes of glutaraldehyde exposure, combined with manual cleaning and alcohol rinse, effectively eliminates mycobacteria.
Area of Science:
- Microbiology
- Infectious Disease Control
- Medical Device Reprocessing
Background:
- Regulatory bodies like the FDA mandate stringent germicide efficacy standards for high-level disinfection (HLD).
- Achieving a 6-log reduction of mycobacteria is critical for HLD claims, especially for gastrointestinal (GI) endoscopes.
- Alkaline glutaraldehyde is a commonly used germicide for endoscope reprocessing.
Purpose of the Study:
- To evaluate the adequacy of current guidelines for high-level disinfection of GI endoscopes.
- To assess the efficacy of alkaline glutaraldehyde under simulated-use conditions.
- To determine the minimum effective exposure time for glutaraldehyde in endoscope reprocessing.
Main Methods:
- Gastrointestinal endoscopes were contaminated with Mycobacterium chelonae.
- Experiments involved standardized manual cleaning, immersion in 2% glutaraldehyde for 10, 20, or 45 minutes, 70% isopropanol rinse, and drying.
- Quantitative cultures were performed at each step to assess microbial reduction.
Main Results:
- Manual cleaning alone reduced mycobacteria by 4 logs.
- Exposure to glutaraldehyde for 10, 20, or 45 minutes, followed by an alcohol rinse, consistently achieved the required 6-log reduction.
- The complete reprocessing protocol, including manual cleaning, glutaraldehyde immersion, and alcohol rinse, ensured mycobacterial elimination.
Conclusions:
- Current FDA guidelines for high-level disinfection of GI endoscopes using alkaline glutaraldehyde are appropriate.
- A minimum of 10 minutes of glutaraldehyde exposure at room temperature is sufficient when combined with manual cleaning and alcohol rinse.
- Alcohol rinse plays a crucial role in drying and provides additional bactericidal effects.