High-level disinfection of gastrointestinal endoscopes: are current guidelines adequate?
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.
Kovacs
B J
BJ
Department of Microbiology, Loma Linda University Medical Center, California 92350, USA.
Chen
Y K
YK
Kettering
J D
JD
Aprecio
R M
RM
Roy
I
I
D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000592:standards*; D020776:Endoscopes, Gastrointestinal; D004866:Equipment Contamination; D000431:Ethanol / Q000494:pharmacology; D005976:Glutaral / Q000494:pharmacology; D016926:Mycobacterium chelonae / Q000187:drug effects; D017410:Practice Guidelines as Topic
D004202:Disinfectants; D000431:Ethanol; D005976:Glutaral