How can you get a salivary gland infection ?

Dehydration.: Although viral parotitis may be related to bloodstream spread of mumps or other viruses, bacterial parotitis generally occurs in patients who get dehydrated with plugging of secretions in stenson's duct (where the saliva drains into the mouth) and bacterial infection, often staph, behind it.

Salivary gland: Immune deficiency, alcohol, drugs, salivary gland/duct stone, high calcium level.

Dehydration: A common cause is dehydration leading to low saliva production. This lack of outflow leads to bacterial inflow from the mouth that can infect the salivary gland. Partial blockage of a salivary duct by a stone or mucous plug can do the same thing.