what causes middle ear infections
Ear Infections-Cause. Middle ear infections are caused by bacteria and viruses. Swelling from an upper respiratory infection or allergy can block the eustachian tubes, which connect the middle ears to the throat. So air can't reach the middle ear. This creates a vacuum and suction, which pulls fluid and germs from the nose and throat into the middle ear. The swollen tube prevents this fluid from draining. The fluid is a perfect breeding ground for bacteria or viruses to grow into an ear infection.