In short, sialadenitis is a disorder of the salivary gland. One of several related disorders, this condition is caused by a painful bacterial infection in a person’s salivary gland. Many times, this infection is caused by staphylococcus or anaerobic bacteria. According to researchers at Harvard Medical School, sialadenitis is most common in elderly adults and very young infants.
Symptoms include a painful lump in the cheek or under the chin, or foul-tasting pus released into the mouth from the salivary duct. In severe cases, the person may experience flu-like symptoms, including a fever and chills. The most severe cases usually occur in elderly people who do not receive treatment for their symptoms… (American Health Advantage)