Tigecycline, a new glycylcycline antibiotic, has shown promising in vitro activity against many common pathogens, including multidrug-resistant strains. To determine the activity of tigecycline against a broad range of pathogens from diverse populations and geographic areas, the Tigecycline Evaluation and Surveillance Trial (TEST Program) commenced in 2003. This study evaluated the activity of tigecycline and commonly used antimicrobials against 6792 clinical isolates from 40 study centers in I I countries. Tigecycline was the most active agent tested against Gram-positive facultative species including inultidrug-resistant strains. MIC90 results (mu g/mL) for tigecycline against Enterococcus fecalis, Enterococcus faecium, Staphylococcus aureus, Streptocoecus agalactiae, and Streptococcus pneumoniae were 0.12, 0.12, 0.25, and 0.25 mu g/mL, respectively. Tigecycline was active against Enterobacteriaceae with an MIC90 of I mu g/mL. Haemophilus influenzae was very susceptible to tigecycline with an MIC90 of only 0.25 mu g/mL. Pseudomonas aeruginosa was the least susceptible organism tested against tigecycline. Tigecycline appears to be a promising new glycylcycline agent for the treatment of many types of pathogens with varying resistance phenotypes. (c) 2005 Elsevier lnc. All rights reserved.