Surfactants antibacterial action

Gillissen [104] finds that the antibacterial action of tyrothricin is influenced by the presence of solubilizers. Cationic surfactants have a synergistic effect (as mentioned above) on its activity against Gram-positive and Gram-negative bacteria, whereas polysorbate 80 inhibits its activity. It is thus important that these effects are borne in mind, and a compromise must be found between the stability and incompatibility characteristics of the solution and the activity of the product. The complexity of the situation is revealed by the fact that the activity of bacitracin is enhanced by the presence of cationic and non-ionic surfactants [106] but decreased by anionic agents. The effect of non-ionic surfactants on the bactericidal activity of tyrothricin has been measured [107]. Some results are shown in Table 6.11. 

The bisbiguanide chlorhexidine (Fig. 3.16) is a powerful antibacterial agent and its actions are related to those of other cationic surfactants that are effective antibacterial agents. The charged groups in the molecules bind to the bacterial membrane, thus dismpting the functioning of the cell. 

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