Subinhibitory concentrations of rokitamycin alter the adherence of Staphylococcus aureus to human cells

Bacterial adhesion to human cells is the result of complex interactions between bacterial surface ligands, adhesins, and host receptors. During antimicrobial therapy there are body concentrations of antibiotics lower than the MIC (sub-MICs) which may induce various changes in bacterial properties, including some that interfere with the ability of bacteria to adhere to epithelial cells. Subinhibitory concentrations of rokitamycin (macrolide) have been observed to alter the adherence of Staphylococcus aureus strains to human buccal cells. In the control test there was an average of 46.5 cells bearing ≥ 50 bacteria per 100 buccal cells, while the corresponding average numbers of cells after incubation of bacteria with 1/2, 1/4, 1/8, and 1/16 of the MIC of rokitamycin were 15.9, 24.0, 33.8, and 44.3, respectively. There was a significant inhibition of adhesion after incubation with 1/2, 1/4, and 1/8 of the MICs of rokitamycin, but not with 1/16 of the MIC.