In vitro activity of grepafloxacin and 25 other antimicrobial agents against Streptococcus pneumoniae: Correlation with penicillin resistance

Strains of Streptococcus pneumoniae from the United States that were suscep tible, intermediately resistant, or highly resistant to penicillin were tes ted for susceptibility to 26 antimicrobial agents that have been used or co nsidered for the treatment of patients with pneumococcal infections. The dr ugs tested included penicillins, one penicillin/beta-lactamase inhibitor co mbination, cephalosporins, macrolides, a lincosamide, fluoroquinolones, and four miscellaneous drugs (vancomycin, rifampin, tetracycline, and trimetho primsulfamethoxazole). The activities of the penicillins and macrolide agen ts were similar, but the activities within the cephalosporin and fluoroquin olone classes were often dissimilar. For the fluoroquinolones, the order of in vitro activity, from most to least active, was grepafloxacin, sparfloxa cin, levofloxacin, ciprofloxacin, and ofloxacin. Increased resistance to pe nicillin in the pneumococcal isolates studied correlated with increased res istance to other penicillins, cephalosporins, macrolides, clindamycin, tetr acycline, and trimethoprimsulfamethoxazole but did not correlate with incre ased resistance to the fluoroquinolones, rifampin, or vancomycin. These fin dings may be helpful to health professionals selecting empiric therapy for respiratory tract infections involving S pneumoniae.