SUBLETHAL CONCENTRATIONS OF CLARITHROMYCIN INTERFERE WITH THE EXPRESSION OF STAPHYLOCOCCUS-AUREUS ADHESIVENESS TO HUMAN-CELLS

It has been known for some time that some antibiotics, generally at su b-lethal concentrations, are able to alter the morphology and the shap e of bacteria. However, more subtle molecular alterations can also be present, such as disorganization of bacterial surface architecture, wh ich leads to changes in the surface electrical charge that can influen ce the forces of attraction or repulsion responsible for interaction o f bacterial surfaces with environmental surfaces. Bacterial adhesion t o epithelial cells is a phenomenon regulated by these mechanisms. Clar ithromycin, a new macrolide, at sub-inhibitory concentrations from 1/2 to 1/16 of the MIC, that is to say, from 0.12 to 0.015 mug/ml, signif icantly reduces adhesion of Staphylococcus aureus to human buccal epit helial cells. Clarithromycin, as other antibiotics that interfere with the bacterial protein synthesis, should also be able to disturb the s ynthesis of adhesins. These are ligand molecules located on the surfac e of bacteria, and thus reduce the ability of bacteria to bind specifi cally to complementary molecules on the surfaces of epithelial cells w hich is necessary for host colonization.