In vitro activity of tigecycline and occurrence of tetracycline resistance determinants in isolates from patients enrolled in phase 3 clinical trials for community-acquired pneumonia

ABSTRACTThe in vitro activity of tigecycline was evaluated against baseline pathogens isolated from patients enrolled in phase 3 clinical trials for communityacquired pneumonia conducted in 29 countries worldwide. Tigecycline was active against the most prevalent pathogens, including Streptococcus pneumoniae (MIC90 0.06 mg. L), Staphylococcus aureus (MIC90 0.25 mg. L), Haemophilus influenzae (MIC90 0.5 mg. L) and Klebsiella pneumoniae (MIC90 1 mg. L). Twelve isolates of S. pneumoniae expressing tet(M) and two isolates of K. pneumoniae producing extended-spectrum b-lactamases isolated during the study were susceptible to tigecycline. The excellent in vitro activity of tigecycline against these clinical isolates confirmed its potential utility against pathogens associated with community-acquired pneumonia.