Comparative in vitro activity of telithromycin and beta-lactam antimicrobials against community-acquired bacterial respiratory tract pathogens in the United States: Findings from the PROTEKT US study, 2000-2001

Background: Telithromycin is a new ketolide antimicrobial that was developed to provide good activity against resistant respiratory tract pathogens. PROTEKT US (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin in the United States) is a multicenter in vitro surveiltance study that was initiated in 2000 to chart the emergence and spread of antimicrobial-resistant pathogens in patients with community-acquired respiratory tract infections (CARTIs). Objective: This article reports first-year results from PROTEKT US pertaining to the comparative in vitro activity of telithromycin and beta-lactam antimicrobials against community-acquired bacterial respiratory tract pathogens. Methods: Data were compiled on the comparative in vitro activity of telithromycin and beta-lactams against Streptococcus pneumoniae (10,103 isolates), Streptococcus pyogenes (3918 isolates), and Haemophilus influenzae (2706 isolates). Minimum inhibitory concentrations (MICs) and susceptibilities were determined according to National Committee for Clinical Laboratory Standards methods. Results: In total, 38.8% (3920/10,103) of pneumococcal isolates were not susceptible to penicillin (12.5% [1266] intermediate [MIC, greater than or equal to0.12-1.0 mg/dL], 26.3% [2654] resistant [MIC, greater than or equal to2 mg/dL]). Telithromycin was highly active against S pneumoniae (MIC required to inhibit 90% of isolates [MIC90], 0.5 mg/L), with 99.6% (10,062/10,103) of isolates fully susceptible (MIC, : less than or equal to1 mg/L). Based on MIC(90)s, the rank order of antimicrobial activity was telithromycin (0.5 mg/L), followed by amoxicillin/clavulanate (2 mg/L), penicillin (4 mg/L), and cefuroxime (8 mg/L). Telithromycin retained high activity (MIC 90, 1 mg/L) against penicillin-resistant pneumococci that showed high levels of coresistance to beta-lactams. All isolates of S pyogenes were fully susceptible to the beta-lactams tested. Beta-lactamase production was common among H influenzae isolates (28.3% [765/2706]). Telithromycin was active against H influenzae (MIC90, 4 mg/L), irrespective of beta-lactamase production. Conclusion: Overall, these findings, from the first year of PROTEKT US support the potential value of telithromycin in the treatment of CARTIs. Copyright (C) 2004 Excerpta Medica, Inc.