Efficacy comparison of glutaraldehyde-phenate vs other glutaraldehydes in fomites disinfection, by different methods

To compare the efficacy of glutaraldehyde-phenate against four other glutaraldehydes.

We use two methods: (1) Bacteriostatic method- With 97 microrganisms of 8 different species. (2) Bactericide method- With a low contamination (10(4)cfu) plus organic soil (simulating the work conditions of glutaraldehyde when we wash fomites before disinfection), we used six microorganisms (the most sensitive and the most resistant, according to the first method, of three species: P. aeruginosa, R. pneumoniae and S. aureus) in different times and concentrations.

Glutaraldehyde-phenate is the most active against Gram-positives, but less with Gram-negatives. However when we study the total effect of the five glutaraldehydes, there are no significant differences among the mean of the minimum inhibitory concentrations (MICm). With the bactericide method the total bactericide effect (0% survival) is easily achieved with the five glutaraldehydes at 2% dilution, but when we reduced the concentration (1/16) we needed 60 minutes for glutaraldehyde-phenate and 15-30 minutes with the rest.

The five products have got a similar efficacy in higher concentration, but at 1/16 dilution glutaraldehyde-phenate need increase the contact-time on the fomite.