Middle ear infections, a.k.a. otitis media – Middle ear infections occur behind the ear drum and can be caused by either bacterial or viral infections. These infections may be triggered by allergies, infections elsewhere in the body, or a blocked Eustachian tube that connects the ear to the back of the nose. This is the most common type of infection in children, although it can occur in adults as well. In some cases fluid may linger in the middle ear and cause muffled hearing. Treatment of otitis media depends on the cause of the infection and ranges from oral antibiotics to surgical insertion of a pressure equalization tube to drain fluid from behind the ear drum. Often enlarged adenoid tissue in the back of the nose is the root cause of the problem by obstructing the Eustachian tube. In children, an adenoidectomy is sometimes necessary in conjunction with tubes.