Acute infection of the parotid gland can be caused by a variety of bacteria and viruses. Acute bacterial suppurative parotitis is caused most commonly by Staphylococcus aureus and mixed oral aerobes and/or anaerobes. It often occurs in the setting of debilitation, dehydration, and poor oral hygiene, particularly among elderly postoperative patients.
The epidemiology, clinical manifestations, microbiology, diagnosis, and treatment of suppurative parotitis will be reviewed here. Deep neck space infections and salivary duct stones are discussed separately. (See "Deep neck space infections" and "Salivary gland stones".)
ANATOMY AND PATHOGENESIS
The parotid glands are located on the sides of the face anterior to the external auditory canal, superior to the angle of the mandible, and inferior to the zygomatic arch. Most of the parotid gland is superficial to the masseter muscle. The salivary gland consists of 20 to 30 intraparotid and periparotid lymph nodes with lymphatic drainage from the ipsilateral side of the face and forehead, including the auricular region and the external auditory canal . Stensen's duct arises from the anterior border of the parotid gland and is 4 to 7 cm long, narrows to 1.2 mm at an isthmus, and the os is 0.5 mm and is opposite the upper second molar (figure 1).
Acute bacterial suppurative parotitis may occur when salivary stasis permits retrograde seeding of the Stensen's duct by a mixed oral flora . Ductal obstruction by calculi or tumor may predispose to suppuration. Abscess formation may also arise by contiguous infection or hematogenous seeding to the intraparotid or periparotid lymph nodes .
EPIDEMIOLOGY AND RISK FACTORS
Suppurative parotitis typically occurs in elderly postoperative patients who are dehydrated or intubated, although it may also be seen in outpatients [2,3]. Other predisposing factors include recent intensive teeth cleaning, use of anticholinergic drugs and other drugs that reduce salivary flow, malnutrition, salivary calculi with obstruction, and neoplasm of the oral cavity . Infection of embryogenic cysts, such as the first branchial cleft, may result in frequent suppuration of the parotid gland .