In vitro antimicrobial activity of 18 phenothiazine derivatives: structure-activity relationship.

The antimicrobial activity of 18 phenothiazine derivatives has been evaluated against aerobic and anaerobic bacteria. The mean of the MIC reveals five active drugs against the bacterial strains tested: thioridazine, chlorpromazine, trifluoperazine, fluphenazine and triflupromazine. The other derivatives are less active and some show no antimicrobial activity. It seems that in vitro antibacterial activity alone is insufficient to explain certain intestinal diseases linked to the use of these molecules in psychiatry.