Antiseptic mouthrinse-induced microbial cell surface alterations

This study determined the effect of an essential oil-containing mouthrinse, Listerine Antiseptic, on microbial cell surface morphology using scanning electron microscopy. Twenty-four hour cultures of C. albicans, A. viscosus, S. sanguis, F. nucleatum, and A. actinomycetemcomitans were harvested and washed in buffer. Triplicate samples were overlaid on poly-L-lysine coated coverslips, immersed in either Listerine or buffer for 30 seconds, fixed in glutaraldehyde followed by post-fixing in 1% osmium tetroxide, dehydrated, and embedded in Peldri II. Exposure of the microorganisms to Listerine Antiseptic for 30 seconds resulted in distinct morphological alterations of cell surfaces suggestive of loss of cell surface integrity. The extent of alteration varied among the structurally different species; cell surface roughening was mild in S. sanguis but extensive in the other microorganisms which developed distinct surface blebs and other abnormalities after the 30-second exposure. These results suggest that a brief exposure to Listerine produces significant morphological changes which may be associated with cell death and may help explain the alteration of surface-associated activities demonstrated in previous studies.