A telithromycin (TEL) kill-kinetics study was conducted with 120 clinically significant Streptococcus pneumoniae isolates (60 susceptible and 60 highly resistant to erythromycin). Time-kill curves were performed using different antibiotic concentrations. The minimum inhibitory concentrations (MICs) of TEL were low for both erythromycin-susceptible (MIC < or = 0.016 mg/L) and erythromycin-resistant strains (MIC < or = 0.25 mg/L). TEL showed 99.9% killing of all erythromycin resistant strains at 18-24 h of incubation. Even for strains with erythromycin MICs > or = 64.0 mg/L, TEL was uniformly bactericidal at 0.25 mg/L.