Chlorhexidine Gluconate-Induced Morphological Changes in Gram Negative Microorganisms

Specific changes in the morphology of Enterobacter cloacae, Pseudomonas aeruginosa, and Serratia marcescens after treatment with minimal inhibitory concentrations (MIC) of chlorhexidine gluconate were observed by means of scanning electron microscopy (SEM). These changes include deformation and/or degradation of cell walls as well as pleomorphism, giant cell formation and clustering of damaged bacterial cells. This morphological study on chlorhexidine-treated Gram-negative bacteria supports a predominantly membranotropic mechanism of action of chlorhexidine antiseptics and disinfectants. Chlorhexidine is also active towards immature external bacterial structures at a stage of their development when they are still inside the cell.