Susceptibility of recent clinical isolates of Streptococcus pneumoniae to 17 antibiotics

Because of the recent emergence of strains of Streptococcus pneumoniae highly resistant to penicillin and other antibiotics, we did antibiotic susceptibility testing of 74 strains of S. pneumoniae isolated from recent clinical materials. Six penicillins, 6 cephalosporins and 5 other potentially useful antibiotics were tested by the agar dilution method. No pneumococci highly resistant to penicillin G and other antibiotics were found. However, there were several strains with relative increase in resistance to penicillin G (MIC 0-125 to 0-5 μg/ml). A high percentage of strains were also found to be resistant to tetracycline.