Glutaraldehyde

Two-percent glutaraldehyde has sufficient bactericidal and yeasticidal activity in 3 min, mycobactericidal activity in 10 min and fungicidal activity in 30 min. The antimicrobial activity of glutaraldehyde is explained by protein coagulation and inhibition of macromolecular synthesis. Cell wall and membrane modifications are cellular defence mechanisms. Glutaraldehyde can significantly reduce biofilm formation in P. aeruginosa and has low to moderate biofilm removal rates (2%–82%). Biofilm fixation by glutaraldehyde is usually strong (62%–97%). Susceptibility to glutaraldehyde is not significantly altered by exposure of E. coli, Salmonella spp. and P. aeruginosa to subinhibitory concentrations. Cross-tolerance to other aldehydes may occur in E. coli, Halomonas spp. and B. cepacia. Hydrogen peroxide has the ability to induce a function that reduces the killing effect of aldehydes in E. coli. Few isolates of M. chelonae from endoscope washer-disinfectors were resistant to glutaraldehyde in suspension and carrier tests and also caused endoscope-associated pseudo-outbreaks. Very few M. gordonae isolates were insufficiently reduced by 2.5% glutaraldehyde in 10 min in suspension tests. Very few P. aeruginosa isolates were resistant to glutaraldehyde in suspension tests and caused an endoscope-associated pseudo-outbreak. The overall probability of resistance to glutaraldehyde of practical relevance is very low for most species in the absence of biofilm, with mainly M. chelonae having a higher probability of resistance.