To compare the efficacy and safety of tigecycline with those of levofloxacin in the treatment of subjects with CAP requiring hospitalization. The co-primary efficacy endpoints in the study will be the clinical response in the clinically evaluable population and the clinical response in the clinical modified intent-to-treat population at the TOC visit. The primary efficacy analyses will first determine whether tigecycline is noninferior to levofloxacin. If tigecycline is found to be noninferior, the analyses will determine whether tigecycline is statistically better than levofloxacin.