<s>[INST] What Are Middle Ear Infections? [/INST] Ear infections happen when viruses or bacteria get into the middle ear, the space behind the eardrum. When a child has an ear infection (also called otitis media), the middle ear fills with pus (infected fluid). The pus pushes on the eardrum, which can be very painful. Source: KIDS HEALTH ORG. Link: https://kidshealth.org/en/parents/otitis-media.html. Field: Otolaryngology. Disease: Ear Infection </s>