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

Area of Science:

• Biomaterials Science
• Microbiology
• Dental Research

Background:

• Streptococcus mutans (S. mutans) is a primary pathogen in dental caries.
• Inhibition of S. mutans adherence to tooth surfaces is crucial for preventing cavities.
• Chitosan, a biopolymer, exhibits antimicrobial properties with potential applications in oral health.

Purpose of the Study:

• To evaluate the in vitro efficacy of high molecular weight chitosan (HMWCh) and low molecular weight chitosan (LMWCh) in inhibiting S. mutans adherence.
• To assess the influence of pH and ionic strength on chitosan's anti-adherence activity.
• To determine the minimum inhibitory concentration (MIC) and antibacterial activity of chitosan.

Main Methods:

• In vitro evaluation of HMWCh and LMWCh.
• Assessing adherence of S. mutans (ATCC 25175) to artificial saliva-coated hydroxyapatite beads.
• Analysis of pH, ionic strength, MIC, and antibacterial activity.

Main Results:

• HMWCh, under specific pH (7.0) and ionic strength conditions, formed rigid meshes that aggregated and entrapped S. mutans.
• LMWCh produced smaller aggregates with less interaction capacity.
• The MIC for HMWCh was 0.5 g%, indicating bacteriostatic action.

Conclusions:

• HMWCh demonstrates significant potential to inhibit the specific adsorption of S. mutans to saliva-coated hydroxyapatite beads.
• The conformational changes and aggregation properties of HMWCh are key to its inhibitory effect.
• HMWCh is a promising agent for developing strategies against S. mutans-associated dental caries.