Evaluation of three glutaraldehyde-based disinfectants used in endoscopy

The European suspension test was applied to compare the in vitro activity of three glutaraldehyde-based disinfectants: a 1:10 dilution of a 10% glutaraldehyde solution containing 0.5% phenylphenol-0.1% amylphenol, a 2% acid glutaraldehyde solution, and a 2% alkaline glutaraldehyde solution. The microbicidal effect of the disinfectants was evaluated by counting surviving cells of three indicator microorganisms (Pseudomonas aeruginosa, Mycobacterium chelonae and phage f2) after exposure times of 5, 10, 20 and 40 min to the agents at 20 degrees C. An inactivation factor (IF) of > or = 5 log10 was used as the criterion for effective disinfection. This IF was achieved with every microorganism/disinfectant combination after 5 min exposure except in experiments with phage f2 and the 1% glutaraldehyde-based disinfectant. The diminished inactivation noticed with the 1% glutaraldehyde-based disinfectant supports the recommendation to use a disinfectant containing a minimum of 2% glutaraldehyde for high level disinfection.