To compare the efficacy and safety of the tigecycline regimen with that of the imipenem/cilastatin regimen in subjects with nosocomial pneumonia.

Inclusion Criteria:

• Male or female subjects over 18 years of age. Bulgaria Only: Male or female subjects over 18 years of age and under 70 years of age.
• Subjects known or suspected to have acute hospital-acquired pneumonia.

Exclusion Criteria:

• Presence of any of the following pulmonary conditions: cystic fibrosis; pulmonary malignancy (either primary or metastatic); known bronchial-obstructive or post obstructive pneumonia; pulmonary abscess; empyema; known or suspected active tuberculosis; bronchiectasis; sarcoidosis; known or suspected pulmonary infection caused by Pneumocystis carinii, mycobacteria, fungi, parasites, or viruses (Subjects with COPD are not excluded)
• Suspected or known Legionella infection
• Concurrent hemodialysis, hemofiltration, peritoneal dialysis, or plasmapheresis