Inclusion Criteria:

• Clinical diagnosis of acute sinusitis with signs and symptoms present for >7 days but < 28 days as defined by A), radiographic, and B) clinical criteria, as follows:

  1. The presence of 1 or more of the following on a radiographic paranasal sinus film (Waters' view) or limited CT scan:

     • evidence of air-fluid levels
     • opacification

  2. The presence of at least one major and one minor symptom as defined in the list below:

     • Major Symptoms

       • Purulent anterior or posterior nasal discharge
       • Unilateral moderate or severe facial pain or malar tenderness

     • Minor Symptoms

       • Cough or frequent throat clearing
       • Frontal headache
       • Halitosis
       • Fever (oral > 38.0°C/100.4°F, tympanic > 38.5°C/101.2°F)
       • Purulent secretions obtained via middle meatus secretion sampling using nasal endoscopic technique; the specimen sent for Gram stain, culture and susceptibility testing prior to initiation of antimicrobial therapy

     Exclusion Criteria:

• History of chronic sinusitis defined as greater than four weeks of continuous symptoms (patients with history of sinus surgery may be included; patients with recurrent sinusitis may be included)
• Known bacteremia, meningitis or infection infiltrating the tissues neighboring the sinuses
• Received systemic antibacterial therapy likely to be effective in sinusitis for more than 24 hours within 7 days of enrollment
• A requirement for concomitant systemic antibacterial therapy with agents other than those specified in this protocol
• Known immunodeficiency diseases including AIDS (CD4 <200)
• On topical nasal or systemic corticosteroids, unless they have been on a stable dose for > 4 weeks prior to enrollment
• History of allergy to quinolone antibiotics or related compounds
• Pregnant or breast feeding
• Of childbearing potential in whom pregnancy cannot be excluded by a negative pregnancy test and who are not using reliable barrier method of contraception
• Received an investigational drug in the past 30 days
• Unable to take oral medication
• Known to have congenital or sporadic syndromes of QTc prolongation or receiving concomitant medication reported to increase the QTc interval (e.g. amiodarone, sotalol, disopyramide, quinidine, procainamide, terfenadine)
• End stage liver cirrhosis (class Child-Pugh C)
• Severe renal impairment requiring dialysis
• Previous history of tendinopathy associated with quinolones
• Any symptoms that suggest that the patient's current illness is allergic rhinitis (e.g., repetitive sneezing, itchy nose or eyes, provocation by an allergen) and not acute bacterial sinusitis
• Diagnosis of rapidly fatal illness with a life expectance of less than 6 months
• Previously enrolled in this clinical study
• Uncorrected hypokalaemia