In vitro activity of a novel ketolide ABT-773 against invasive strains of Streptococcus pneumoniae

New ketolides such as ABT-773 are a promising group of antibiotics in an er a of increasing antibiotic resistance. We tested 704 invasive strains of St reptococcus pneumoniae collected from 1990 to 1998. Overall resistance was 8.3, 4.6, 4.5 and 3.6% for penicillin, cefuroxime, erythromycin and clarith romycin, respectively. By using a recommended breakpoint for susceptibility of <0.5 mg/L, no strains showed reduced susceptibility to ABT-773. ABT-773 was very active against all penicillin-resistant strains (MIC > 2 mg/L, wi th a mean geometric mean <0.06 mg/L), and against all 33 erythromycin-resis tant strains, irrespective of the mode of resistance [mef- or erm(B)-mediat ed]. ABT-773 is a very active and promising agent against invasive strains of S. pneumoniae, including multiresistant strains.