Tetracycline-Resistant Group a Streptococci and Pneumococci

Abstract
The in vitro susceptibility to tetracycline, methacycline and doxycycline of 130 strains of group A streptococci and 136 strains of pneumococci was determined through the agar plate dilution method. 6% of the group A streptococci and 3% of the pneumococci were found to be resistant (not inhibited by 1 μg active substance/ml). 3% of the group A streptococci were not inhibited by 64.0 μg tetracycline/ml. The frequency of tetracycline-resistant group A streptococci was lower than found by others during the last 5 years, while the frequency of tetracycline-resistant pneumococci corresponded well with earlier reports.