Triclosan against bacteria

Bacteriostatic action of Triclosan

Various modes of action have been described for Triclosan. Studies indicate that Triclosan especially affects the cytoplasmic membrane of bacteria. At bacteriostatic active concentration levels, the metabolism of lipids (Russel et al. 2004, Guillen et al. 2004, Villalain et al. 2001) as well as the uptake of essential amino acids, uracil and other nutrients is impacted. Higher bactericidal concentrations of Triclosan cause structural disorganization of the cytoplasmic membrane and leakage of low-molecular-weight cellular contents (Regös & Hitz, 1974), resulting in a major impact on energy metabolism and finally cell death.

In comparison to other antimicrobial agents, Triclosan is an extremely efficient bacteriostatic active at low concentrations. Its minimum inhibitory concentration (MIC) values against most bacteria are in the low ppm range. This means that very small concentrations left on the skin or mucous membranes after application of a Triclosan-containing product, are able to inhibit the growth of various malodor-generating bacteria or pathogenic microorganisms. One way to visualize the bacteriostatic efficacy of Triclosan on treated surfaces is the agar diffusion test (see Figure 1).




Figure 1:
The pictures show bacterial growth after the incubation period. Each agar plate contains a paper disc treated with 40 µl of a 0.1% Triclosan solution resulting in a final amount of 25 ppm on the paper disk. The paper disk is laid on a CASO-agar containing the test bacteria. After 24 hours of incubation, the bacteria not inhibited by Triclosan show visual growth. The pictures display clear growth–free zones around the paper discs due to migration of ppm amounts of Triclosan into the surrounding agar.

Bactericidal action of Triclosan

At higher concentrations, Triclosan in disinfecting formulations also exhibits a fast killing activity on pathogenic bacteria. The severe disorganization of bacterial cells and inhibition of metabolism caused by bactericidal concentrations of Triclosan inevitably leads to the bacterial cell’s death.Various studies on the bactericidal activity of Triclosan have been published (Jones et al. 2000). For more information on bactericidal activity of Triclosan, please contact BASF.

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