Low and high molecular weight chitosans interactions with Streptococcus mutans: an in vitro study

We evaluated the in vitro capacity of high and low molecular weight chitosans (HMWCh and LMWCh) to inhibit the adherence of strains of S. mutans obtained from the American Type Culture Collection (ATCC,25175) to artificial saliva-coated hydroxiapatite beads. The effect of these biopolymers was assessed in terms of pH, ionic force, minimum inhibitory concentration (MIC) and antibacterial activity. The results show that HMWCh is modified by a rise in pH (7.0) and ionic strength. The induced conformational changes lead to the formation of rigid meshes capable of aggregating and entrapping S. mutans. This process is associated to the properties of HMWCh. LMWCh gave rise to smaller aggregates that exhibited a comparatively reduced interaction capacity. The MIC for HMWCh was 0.5 g% and evidenced the bacteriostatic action of the aggregates. We conclude that HMWCh would exert an inhibitory effect on the process of specific adsorption of S. mutans to saliva-coated hydroxiapatite beads.