Tigecycline displays in vivo bactericidal activity against extended-spectrum-β-lactamase-producing Enterobacteriaceae after 72-hour exposure period.

Progressively enhanced activity of a humanized tigecycline (TGC) regimen was noted over 3 days against an extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli isolate and an ESBL-producing Klebsiella pneumoniae isolate. Bacterial density reduction approximated 3 log(10) approaching bactericidal activity at 72 h. This level of activity has not been previously noted for compounds such as tetracyclines, normally considered bacteriostatic antimicrobials. Extended regimen studies in vivo may aid in better delineation of antimicrobial effects, producing improved correlation with clinical outcomes.