The most common things seen in the salivary glands include autoimmune disorders and infections.
Mumps causes a viral parotitis.
Bacterial parotitis is almost always caused by Staphylococcus aureus and often occurs in patients who are dehydrated, diabetic, and in the hospital. The dehydration leads to inspissation of secretions with subsequent overgrowth of Staph. Often, pus can be expressed from Stenson's duct and these patients are treated generally with high dose intravenous antibiotics as well as local applications of heat and sialagogues such as lemon drops. They generally do well. Occasionally, they will need to be drained surgically.