Antimicrobial Susceptibility of Respiratory Tract Pathogens in Japan During PROTEKT Years 1–5 (1999–2004)

Abstract

Susceptibility to a range of antimicrobial agents was determined among isolates of Streptococcus pneumoniae, Streptococcus pyogenes, and Haemophilus influenzae collected in 12 centers throughout Japan during years 1–5 (the respiratory seasons of 1999–2004) of the longitudinal Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin study. The most frequent source of isolates of S. pneumoniae was from patients with community-acquired pneumonia (CAP) (25.3%). Reduced susceptibility to penicillin or erythromycin resistance was common among S. pneumoniae isolates (30.9–44.5% and 77.2–81.9%, respectively). The macrolide MIC₅₀ for S. pneumoniae was ≥128 μg/ml (azithromycin and erythromycin) and ≥64 μg/ml (clarithromycin). The erm(B) genotype accounted for the most erythromycin-resistant isolates in each study year. H. influenzae isolates were most commonly derived from patients with CAP (26.2%). The proportion of H. influenzae isolates that were β-lactamase positive ranged between 4.3% and 9.7%. The prevalence of β-lactamase–negative ampicillin-resistant isolates increased from 0.4% to 2.6% between years 1 and 4 then to 19.7% in year 5. S. pyogenes isolates were highly susceptible to most antimicrobial agents except macrolides and tetracycline. Telithromycin was highly active against all three pathogens examined throughout the study.