Enhanced antibacterial and anti-quorum sensing activities of triclosan by complexation with modified ß-cyclodextrins.

ABSTRACT

Triclosan (TCS), an antimicrobial agent widely used in consumer and medical products, was complexed with 2-hydroxypropyl-ß-cyclodextrin (HPßCD) and methyl-ß-cyclodextrin (MßCD). Phase-solubility studies indicated that inclusion complexes of 11 stoichiometry were formed and allowed estimation of the associated equilibrium constants and free-energy changes. At the highest cyclodextrin concentrations investigated, an almost 20-fold increase in the apparent water solubility of TCS was determined. Susceptibility tests against Escherichia coli and Staphylococcus aureus showed that the TCS-HPßCD and TCS-MßCD complexes exhibited antibacterial properties higher than those of uncomplexed TCS. The two complexes were also found capable of interfering with cell-to-cell communication mechanisms in the C. violaceum model system relying on N-acylhomoserine lactone autoinducers. The inhibitory activity of TCS increased significantly upon inclusion of the drug in HPßCD or MßCD, with small differences between the two CDs. The results obtained suggest that the investigated complexes could be used for treating infections caused by TCS-susceptible pathogens or for preventing biofilm formation on indwelling medical devices such as catheters, stents and orthopedic implants.