• To evaluate and compare the overall incidence of MS disorders in pediatric patients that occurred after the first dose of levofloxacin with that of 'standard' nonfluoroquinolone therapy. [ Time Frame: Within 60-day period after the first dose of study medication in the prior Phase 3 tretament protocol. ] [ Designated as safety issue: Yes ]
  

• Overall incidence of MS disorders including impaired growth in the 1-year period after the first dose. [ Time Frame: 5 visits (1, 2, 3, 6 and 12 months after 1st dose) ] [ Designated as safety issue: Yes ]
  
• Incidence of each MS disorder that occurred at weight- and nonweightbearing joints in the 60-day, and 1-year periods after the first dose. [ Time Frame: 5 visits (1, 2, 3, 6 and 12 months after 1st dose) ] [ Designated as safety issue: Yes ]
  
• Incidence of each MS disorder in the 60-day period and in the 1-year period, which included impaired growth. [ Time Frame: 5 visits (1, 2, 3, 6 and 12 months after 1st dose) ] [ Designated as safety issue: Yes ]
  

Levofloxacin is an antibacterial agent used for the treatment of a broad spectrum of acute infections in adults. In pediatric patients, clinical trials have suggested that levofloxacin is safe and effective for the treatment of a variety of serious infectious diseases.The purpose of this study is to monitor long-term the incidence of musculoskeletal (MS) disorders in children who have received levofloxacin or a standard therapy for acute bacterial infection.Patients who were enrolled in prior Phase 3 clinical studies of the use of levofloxacin for the treatment of acute infectious disease may be eligible to enroll in this study. The primary assessment of safety is the overall incidence of musculoskeletal disorders that occur during the first 60 days after the first dose of anti-microbial therapy. The specific musculoskeletal disorders to be reported are: tendinopathy (inflammation or rupture of a tendon); arthritis (inflammation of a joint as shown by redness or swelling); arthralgia (pain in a joint, as shown by complaint of pain or by abnormal movement of the joint); gait abnormality (limping or refusal to walk). Other assessments of safety include interviews using standardized questionnaires to assess the occurrence of musculoskeletal adverse events, physical examinations, and measurement of a patient's height over the course of 1 year. Patients who develop one or more musculoskeletal disorders during the first year will be monitored until they have completed puberty (15th birthday for females and 17th birthday for males). The primary hypothesis is that the levofloxacin group will be comparable to the standard non-fluoroquinolone therapy group in the overall incidence of defined musculoskeletal disorders (tendinopathy, arthritis, arthralgia, and gait abnormality) during the 60-day period after the first dose of antimicrobial therapy. No study drug is administered in this study.