This is a prospective (look forward using periodic observations collected predominantly following participant enrollment), long-term, comparative, multicenter, observational study (study in which the investigators/physicians observe the participants and measure their outcomes) to monitor long-term the incidence of musculoskeletal (MS) disorders in children who have received levofloxacin or a standard therapy for acute bacterial infection. Approximately 2500 participants who were enrolled in prior Phase 3 clinical studies of the use of levofloxacin for the treatment of acute infectious disease will be observed in this study. The study consists of 3 phases: a screening phase; a surveillance phase; and a musculoskeletal disorder follow-up phase. Safety evaluations will include assessment of an 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); gait abnormality (limping or refusal to walk). Other assessments of safety will include interviews using standardized questionnaires to assess the occurrence of musculoskeletal adverse events, physical examinations, and measurement of participants height over the course of 1 year.
