[Study of antimicrobial activity of carboxymethyl chitosan zinc complex material against cariogenic bacteria]

To evaluate the antimicrobial activity of carboxymethyl chitosan zinc (CMCSZ) and carboxymethyl chitosan zinc-active peptide complex material (CMCSZP) on oral cariogenic bacteria.

Agar dilution method and K-B disk diffusion susceptibility agents were used to measure the antimicrobial activity of two agents against S.mutans, Lactobacillus, S.sanguinis and Actinomyces viscosus. The former method was used to measure the minimal inhibitory concentration (MIC) and latter was used to measure the inhibitory zone. The effects of pH value, temperature, light, ultraviolet and storage temperature on the active substances were investigated to determine the stability of CMCSZ and CMCSZP. SPSS17.0 software package was used for statistical analysis.

All the bacteria were susceptible to active peptide, CMCSZ and CMCSZP with the MIC of CMCSZ/CMCSZP being 625, 1250, 1250 and 2500 mg/L, respectively. At the same concentration, the inhibitory zone of CMCSZP was significantly bigger than that of CMCSZ. Acidic conditions were conducive to increase the antimicrobial activity of CMCSZ, while the effect on CMCSZP was not significant. CMCSZ and CMCSZP exhibited good stability against light, but their antimicrobial activity gradually weakened as the bath temperature rising. In the temperature of 85 degrees centigrade, their antibacterial activity disappeared.

CMCSZ have CMCSZP had strong antimicrobial activity against 4 kinds of cariogenic bacteria. They have good stability against light, but poor thermal stability. This study provides theoretical foundation for the application of CMCSZ/CMCSZP in prevention of cariogenic diseases.