To evaluate the safety and efficacy of tigecycline in the treatment of subjects with selected serious infections caused by resistant gram-negative bacteria, eg, Acinetobacter baumannii, Enterobacter species, Klebsiella pneumoniae or other resistant gram-negative pathogens, for whom antibiotics have failed or who cannot tolerate other appropriate antimicrobial therapies. The primary efficacy endpoint will be the clinical response.

Inclusion Criteria:

• Male or female subjects aged 18 years or older
• Isolation of a resistant gram-negative pathogen, eg, Enterobacter species, Acinetobacter baumannii, Klebsiella pneumoniae, or other resistant gram-negative pathogens, alone or as 1 isolate of a polymicrobial infection
• Resistant gram-negative organisms are defined by the likely presence of ESBL or related mechanisms which limit the therapeutic alternatives for the treatment of complicated infections

Exclusion Criteria:

• Subjects with any concomitant condition or taking any concomitant medication that, in the opinion of the investigator, could preclude an evaluation of a response or make it unlikely that the contemplated course of therapy or follow-up assessment will be completed or that will substantially increase the risk associated with the subject's participation in this study
• Anticipated length of antibiotic therapy < 7 days
• Known or suspected hypersensitivity to tigecycline or other compounds related to this class of antibacterial agents (eg, tetracyclines, minocycline, doxycycline)