Antibacterial susceptibility among Streptococcus pneumoniae isolated from paediatric and adult patients as part of the PROTEKT US study in 2001-2002

Background: One of the main factors commonly associated with antibacterial resistance among Streptococcus pneumoniae is the age of the patient. The highest rates of resistance have often been reported among isolates from young children. Methods: Data from the PROTEKT US (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin in the United States) surveillance study were examined to determine the level of antibacterial resistance among S. pneumoniae isolates collected in 2001-2002 from different patient age groups in the USA. Results: A total of 10 012 clinical isolates of S. pneumoniae were submitted by 242 centres across the USA and categorized into four patient age groups: infants (0-2 years, n = 1556), children (3-14 years, n=1125), adults (15-64 years, n=4058) and elderly adults (greater than or equal to65 years, n = 3067) (age unknown n=206). With the exception of the fluoroquinolones and linezolid, rates of antibacterial resistance were highest among infants and decreased with increasing patient age. Resistance to penicillin ranged from 33.6% among infants to 17.5% among elderly adults, and erythromycin resistance ranged from 41.1% among infants to 24.0% among adults. In contrast, levofloxacin resistance increased with patient age (from 0.1% to 1.6%). The highest rates of susceptibility were noted for telithromycin and linezolid (greater than or equal to99.6% and greater than or equal to99.8% susceptible isolates, respectively). Conclusions: The PROTEKT US study data confirmed that the highest antibacterial resistance rates were associated with isolates collected from young children (0-2 years). Telithromycin may offer a reliable alternative to first-line drugs in the empirical treatment of community-acquired respiratory tract infections.