Antimicrobial Susceptibility of Streptococcus Pneumoniae, Streptococcus Pyogenes and Haemophilus Influenzae Collected from Patients Across the USA, in 2001-2002, As Part of the PROTEKT US Study

Background: The PROTEKT US (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin in the United States) surveillance programme was started in 2000, to chart the emergence and spread of antimicrobial resistance among isolates of Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae from across the USA.

Methods: In 2001-2002 (Year 2 of PROTEKT US) 242 centres from 46 states and the territory of Puerto Rico submitted a total of 10 012 S. pneumoniae, 4508 S. pyogenes and 3296 H. influenzae isolates from community-acquired respiratory tract infections (CARTIs). Susceptibility testing was performed and interpreted using NCCLS methodology and criteria.

Results: Overall, 35.4% of S. pneumoniae were non-susceptible to penicillin (14.2% intermediate, MIC 0.12-1 mg/L; 21.2% resistant, MIC > or =2 mg/L) and 27.9% were resistant to erythromycin (MIC > or =1 mg/L) (0.2% intermediate, MIC 0.5 mg/L). A total of 105 (1.0%) isolates were resistant to levofloxacin (MIC > or =8 mg/L). More than 99.2% of isolates were susceptible to telithromycin (MIC < or =1 mg/L) irrespective of penicillin and/or erythromycin resistance. All S. pyogenes isolates were susceptible to penicillin (MIC < or =0.12 mg/L) and 5.7% were resistant to erythromycin (MIC > or =1 mg/L) (0.3% intermediate, MIC 0.5 mg/L). The MIC90 of telithromycin for S. pyogenes was 0.03 mg/L. A total of 27.5% of H. influenzae isolates were beta-lactamase producers. Overall, 27.8% were resistant (MIC > or =4 mg/L) and 1.1% were intermediate to ampicillin (MIC 2 mg/L). A total of 96.3% of H. influenzae isolates were susceptible to telithromycin (MIC < or =4 mg/L).

Conclusions: Antimicrobial resistance continues to be a problem in the USA. The ketolide telithromycin continues to show high activity against common CARTI pathogens, including those resistant to beta-lactams and macrolides.