Rapid and severe onset of middle ear infection is a common bacterial infection in children. These infections, particularly when they occur early in life and are recurrent, are associated with considerable disease and can lead to increasingly serious infections. This is a multicenter study to determine the effectiveness of levofloxacin in eliminating bacteria in the middle ear fluid of children between 6 months and 5 years of age with a rapid and severe onset of infection and inflammation of the middle ear (who are at high risk for infections that are difficult to treat). The study consists of a 1-day screening period when patients will be tested for eligibility for the study; a 4 to 6-day treatment, blood collection, possible collection of fluid from the middle ear, and assessment period; and a post-treatment period to assess the status of the middle ear infection. All patients will receive levofloxacin 2 times daily (up to a maximum daily dose of 500 mg) mixed with liquid and taken by mouth for 10 days. Safety evaluations will include laboratory tests, physical examinations, vital sign measurements, and recording of adverse events, including any report of joint pain or signs and symptoms of joint disease. Effectiveness will be assessed by the rate of elimination of the bacteria identified at the start of the study and by signs and symptoms, as well as microscopic evidence that the patient is cured of the middle ear infection. The study hypothesis is that levofloxacin will be effective in eliminating bacteria in the middle ear fluid of children with a rapid and severe onset of infection and inflammation of the middle ear and who are at high risk for infections that are difficult to treat. Levofloxacin 10 milligrams/kilogram (mg/kg) 2 times daily (up to a maximum daily dose of 500 mg) mixed with liquid and taken by mouth for 10 days