inflammation of the lining of the middle ear and one of the most common infections in childhood. In its acute form, it commonly develops in association with an infection of the upper respiratory tract that extends from the nasopharynx to the middle ear through the eustachian tube. The organisms that cause the disease in children under six years of age most commonly are the bacteria Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae. The incidence of H. influenzae otitis has declined in response to a vaccine. Symptoms of otitis media include fever, earache, and sometimes suppuration (discharge of pus). Diagnosis is established by careful visual examination of the tympanic membrane (eardrum) and by techniques (tympanometry) that can provide evidence of fluid behind the eardrum. Antibiotics generally are given for acute otitis because the infection can spread to the nearby bones ( mastoiditis) and the central nervous system ( meningitis). The disease can be complicated by perforation of the eardrum and, in rare cases, by permanent hearing losses that lead to delay in the development of speech and language.