Acute Bacterial Parotitis

Acute bacterial parotitis is suppurative infection of the parotid gland from retrograde spread of oral bacteria along Stensen duct when salivary flow is reduced. Staphylococcus aureus is the commonest cause, followed by streptococci, oral anaerobes and gram negative bacilli.

• Risk factors: dehydration, postoperative state (especially abdominal surgery), old age, malnutrition, poor oral hygiene, anticholinergic drugs, diuretics, Sjogren syndrome, sialolithiasis, HIV, mouth breathing, diabetes.
• Neonates can be affected.

Sudden painful, warm, red, tender swelling of one parotid gland (sometimes both), with trismus, fever, chills; pus expressed from the Stensen duct opening on massage.

• Skin overlying becomes red and shiny; difficulty opening the mouth and eating.
• Differential diagnosis: mumps (bilateral, viral), HIV associated parotid cysts and lymphoepithelial disease, sialolithiasis, parotid abscess, Sjogren syndrome, tumour (pleomorphic adenoma, mucoepidermoid carcinoma), lymphadenitis of intraparotid nodes, dental abscess, facial cellulitis, tuberculosis, sarcoidosis, cat scratch disease.
• Complications: parotid abscess, facial nerve palsy, spread to parapharyngeal space, airway compromise, sepsis, osteomyelitis of the mandible, jugular vein thrombosis, ductal stricture, chronic recurrent parotitis.

Clinical, confirmed by ultrasound.

• Ultrasound (diffuse enlargement, abscess, stones); CT with contrast for deep abscess or suspected tumour.
• Culture of pus from Stensen duct before antibiotics; full blood count, CRP, urea, electrolytes, glucose; blood cultures if febrile.
• Mumps serology and HIV test where relevant; avoid sialography during acute infection.

Hydration, antibiotics and drainage of any abscess.

• Supportive: IV fluids to correct dehydration, oral hygiene with chlorhexidine 0.2 percent rinses, warm compresses, gentle gland massage, sialogogues (lemon drops, sugar free chewing gum), analgesia (paracetamol 1 g, ibuprofen 400 mg), stop anticholinergic drugs if possible.
• Pharmacological: flucloxacillin 1 to 2 g IV every 6 hours (500 mg to 1 g orally four times daily) plus metronidazole 500 mg IV every 8 hours (400 mg orally three times daily) for 10 to 14 days; or amoxicillin clavulanate 1.2 g IV every 8 hours then 625 mg orally three times daily; MRSA risk: vancomycin 15 to 20 mg/kg IV every 12 hours; penicillin allergy: clindamycin 600 mg IV every 8 hours. Children: flucloxacillin 25 mg/kg every 6 hours with metronidazole 7.5 mg/kg every 8 hours. Neonates: cloxacillin 50 mg/kg every 12 hours with gentamicin 5 mg/kg daily.
• Procedures: ultrasound guided needle aspiration; incision and drainage for abscess (Hilton method with blunt dissection to protect the facial nerve); sialendoscopy for stone or stricture.
• Special groups: pregnancy, flucloxacillin or amoxicillin clavulanate; children, weight based doses and exclusion of mumps; HIV, evaluate for lymphoepithelial disease; elderly, careful fluid replacement.
• Red flags: trismus with neck swelling, stridor, facial weakness, fluctuance, fever with toxicity, no response at 48 hours.
• Follow-up: review at 48 hours; ultrasound if not improving; ENT follow up for recurrent episodes.