The efficacies of tigecycline and ceftazidime against fatal pneumonia in rats caused by an extended-spectrum β-lactamase (ESBL)-positive Klebsiella pneumoniae strain or its wild-type (WT) progenitor were compared. Ceftazidime at 12.5 or 50 mg/kg of body weight twice daily (b.i.d.) was effective (50% or 100% rat survival) in pneumonia caused by the WT isolate but unsuccessful (100% rat mortality) in pneumonia caused by the ESBL-positive variant. In contrast, tigecycline at 6.25, 12.5, or 25 mg/kg b.i.d. showed dosage-dependent efficacy up to 100% rat survival irrespective of the ESBL character of the infecting organism. Copyright,
Antimicrobial Agents and Chemotherapy
Department of Medical Microbiology and Infectious Diseases

Goessens, W.H.F, Mouton, J.W, ten Kate, M.T, Sorgel, F, Kinzig, M, & Bakker-Woudenberg, I.A.J.M. (2013). The therapeutic effect of tigecycline, unlike that of ceftazidime, is not influenced by whether the Klebsiella pneumoniae strain produces extended-spectrum β-lactamases in experimental pneumonia in rats. Antimicrobial Agents and Chemotherapy, 57(1), 643–646. doi:10.1128/AAC.01154-12