Study to Demonstrate the Clinical Efficacy of Levofloxacin in the Treatment of Pneumonia

Primary Objective: * The primary objective of the study is to demonstrate the non-inferiority in clinical efficacy at the test of cure (TOC) visit planned 5-7 days after treatment completion of levofloxacin 750 mg once daily (od) in comparison with piperacillin/tazobactam 4 g/500 mg every 8 hours in treating adult patients suffering from mild to moderate hospital-acquired pneumonia. Secondary Objectives: The secondary objectives of the study are: * To assess the bacteriological efficacy at the test of cure (TOC) visit * To assess the clinical and bacteriological efficacy at the end of study (EOS) visit, 28 to 32 days after treatment ends * To assess the tolerability of both drugs