In vitro susceptibility of mutans streptococci to antimicrobial substances as determined by a membrane transfer assay.

The in vitro susceptibilities of seven representative strains of mutans streptococci to three topically applied chemotherapeutic agents were determined by a modified membrane transfer assay. The MBCs of chlorhexidine and I2-KI ranged from 0.5 to 1.0%, while SnF2 was sublethal at the highest concentration tested (8%) in all but one strain (AHT; mode MBC, 8.0%). The proposed in vitro assay may be useful for preclinical screening of potential antimicrobial agents prior to use in the oral cavity.