Susceptibility of Actinobacillus actinomycetemcomitans strains to norfloxacin.

The minimal inhibitory concentration of norfloxacin to Actinobacillus actinomycetemcomitans strains isolated from patients with localized juvenile periodontitis was determined by using an agar dilution method. All the tested strains, including the three reference strains, were susceptible at concentrations lower than the breakpoint used, with 90% of the strains susceptible to 0.125 micrograms/ml.