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 greater than or equal to2 mg/L) and 27.9% were resistant to erythromycin (MIC greater than or equal to1 mg/L) (0.2% intermediate, MIC 0.5 mg/L). A total of 105 (1.0%) isolates were resistant to levofloxacin (MIC greater than or equal to8 mg/L). More than 99.2% of isolates were susceptible to telithromycin (MIC less than or equal to1 mg/L) irrespective of penicillin and/or erythromycin resistance. All S. pyogenes isolates were susceptible to penicillin (MIC less than or equal to0.12 mg/L) and 5.7% were resistant to erythromycin (MIC greater than or equal to1 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 greater than or equal to4 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 less than or equal to4 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.