A trial in which patients over 18 years of age who are hospitalized with community acquired pneumonia and are otherwise eligible for entry into the study are randomly selected to receive one of two treatment regimens. After written informed consent is obtained, patients will receive one of the following two treatment regimens: 1) intravenous administration of azithromycin and ceftriaxone followed by azithromycin tablets, or 2) intravenous administration of levofloxacin followed by levofloxacin tablets. At least four study visits are normally conducted up to approximately one month after starting therapy. The objective of this study is to compare the safety and efficacy of the two treatment regimens.

Inclusion Criteria:

• Patient must be 18 years or older.
• Patient must be hospitalized and require intravenous therapy for treatment of pneumonia.
• Patient must have pneumonia as documented by relevant signs and symptoms and a positive chest X-ray.
• Patients cannot have certain underlying diseases or conditions as defined in the study protocol.

Exclusion Criteria:

• Pregnant women, nursing mothers, or women of childbearing potential not practicing adequate contraception.
• Known or suspected hypersensitivity or intolerance to any quinolone, penicillin, cephalosporin, or macrolide antibiotic.
• Treatment with any systemic antibiotic for 24 hours or longer within 72 hours prior to the baseline visit.
• Subjects with clinically significant renal dysfunction.
• Subjects with clinically significant hepatic dysfunction.
• Subjects with clinically significant cardiovascular disorders.