The effect of Iodine on Streptococcus mutans, Fructosyltransferase & Glucosyltransferase

Objectives: To examine the influence of four types of iodine formulations on Streptococcus mutans in planktonic and biofilm states, and on the extracellular enzymes glucosyltransferase (GTF) and fructosyltransferase (FTF). The purpose of these observations was to find which formulation would be the most affective influencing the dental biofilm. Methods: Four types of iodine formulations were tested: Povidone-iodine dissolved in water (PI/H2O) Povidone-iodine dissolved in tetraglycol (PI/TG). Iodine dissolved in tetraglycol (I2/TG). Iodine dissolved in water (I2+KI/H2O). The effect of iodine on bacterial viability in planktonic environment was examined using the minimal inhibitory concentration (MIC) method. The effect of iodine on the bacterial viability in biofilm was tested in a biofilm model constructed on glass slides, to which the iodine formulations were added. After 18 hr the iodine was washed and the biofilm was stained with various fluorescence markers, distinguishing between the live or dead bacteria under a confocal microscope. The dead and live bacteria were counted using a computer program. The effect of the iodine formulations on the GTF and FTF enzymes was tested using radio active labeled sucrose. Results: All formulations demonstrated antibacterial and anti-enzymatic properties in various levels. The most active antibacterial formulation against planktonic S. mutans was PI/TG (0.267% PI). The most active antibacterial formulation against bacteria in biofilm was the PI / H2O (more than 35 fold dead bacteria than dead bacteria in the control). All of the formulations reduced the enzymatic activity of GTF or FTF in solution or in an immobilized form. Iodine formulations inhibit the immobilized enzymes more efficiently than enzymes in solution. Conclusion: Iodine at different formulations affects bacteria and enzymes of the dental biofilm.

This study was supported in part by the applied grants of the Hebrew University