Acute otitis media (acute ear infection) occurs when there is bacterial or viral infection of the fluid of the middle ear, which causes production of fluid or pus. This may be accompanied by bleeding in the middle ear. Pressure from fluids associated with ear infection may cause the eardrum to rupture. Conversely, a ruptured eardrum can result in ear infection by allowing bacteria or viruses direct entry to the middle ear. Ear infections are most common following respiratory infections, or if the sinuses or eustachian tube are blocked from allergies or enlarged adenoids.