ANTIMICROBIAL ACTIVITY OF JOSAMYCIN AGAINST ERYTHROMYCIN-RESISTANT STAPHYLOCOCCI AS COMPARED TO ROXYTHROMYCIN AND CLARITHROMYCIN

In an in vitro study 246 clinical isolates of erythromycin-resistant s taphylococci from six hospitals in Austria were investigated for susce ptibility to josamycin and other, newer macrolide antibiotics, e.g. ro xithromycin and clarithromycin. 71 strains of Staphylococcus aureus sh owed an MIC greater-than-or-equal-to 4 mg/l and 100 strains of S. aure us showed an MIC greater-than-or-equal-to 256 mg/l. In addition, 25 st rains of coagulase-negative staphylococci resistant to erythromycin at an MIC of greater-than-or-equal-to 4 mg/l were investigated. At an MI C of 2 mg/l 57% of the erythromycin-resistant strains of S. aureus wer e inhibited by josamycin, 25% by clarithromycin and 11.6% by roxithrom ycin. At an MIC of 2 mg/l 13.3% of erythromycin-resistant coagulase-ne gative staphylococci were inhibited by josamycin, 10.7% by clarithromy cin and 9.3% by roxithromycin. This study suggests that josamycin is s till active in vitro against more than 50% of erythromycin-resistant s trains of S. aureus. This drug is also more active than roxithromycin and clarithromycin against erythromycin-resistant S. aureus.