What is the approach to diagnose and manage the causes of parotitis?

Workup of Parotitis

Begin by determining if the parotitis is viral (most commonly mumps) or bacterial, as this fundamentally changes management: viral parotitis requires only supportive care, while bacterial parotitis demands urgent antimicrobial therapy and possible surgical drainage. 1, 2

Initial Clinical Assessment

Key History Elements

• Onset and duration: Acute bilateral or unilateral parotid swelling lasting ≥2 days suggests viral parotitis, typically developing 16-18 days after mumps exposure 1, 3
• Prodromal symptoms: Fever, headache, malaise, myalgia, and anorexia preceding parotid swelling point toward mumps 1, 3
• Vaccination status: Critical for assessing mumps likelihood, though breakthrough infections occur with waning immunity 3
• Risk factors for bacterial infection: Dehydration, malnutrition, immunosuppression, medications causing xerostomia, sialolithiasis, or recent hospitalization 4, 5
• Pattern: Recurrent episodes in children aged 3-6 years suggest juvenile recurrent parotitis from congenital ductal abnormalities 6

Physical Examination Findings

• Parotid gland: Assess for unilateral versus bilateral swelling, tenderness, warmth, and erythema 1
• Stensen's duct: Express the duct opening (opposite upper second molar) to check for purulent discharge—this is pathognomonic for bacterial suppurative parotitis 4, 5
• Systemic signs: Fever and toxicity suggest bacterial infection requiring urgent treatment 4, 5
• Oral cavity: Examine for poor dentition, oral neoplasms, or signs of dehydration 4, 5

Diagnostic Testing

For Suspected Viral Parotitis (Mumps)

• Serum mumps IgM antibodies: Positive in acute infection 1
• Paired acute and convalescent mumps IgG: 4-fold rise indicates recent infection 1
• Buccal swab: Collect around affected parotid gland and Stensen's duct for viral culture or nucleic acid amplification testing (NAAT) 1

Important caveat: Only 30-40% of mumps infections produce typical parotitis; 15-20% are asymptomatic, making diagnosis challenging 1, 2, 3

For Suspected Bacterial Parotitis

• Pus aspiration or expression from Stensen's duct: Send for Gram stain and culture on media supporting aerobic and anaerobic bacteria, mycobacteria, and fungi 4, 5
• Key pathogens: Staphylococcus aureus is most common; anaerobes (pigmented Prevotella, Porphyromonas, Peptostreptococcus, Fusobacterium) are increasingly recognized; gram-negative bacilli in hospitalized patients 4, 5
• Beta-lactamase producers: Isolated in nearly 75% of cases, necessitating appropriate antibiotic selection 4

Imaging Studies

• Ultrasound: First-line imaging to differentiate parotid from extraparotid masses and assess for abscess formation 1, 6
• CT with IV contrast: Use when ultrasound is inconclusive or to evaluate for abscess requiring drainage 1
• MRI with and without contrast: Provides comprehensive assessment of disease extent, particularly useful for chronic or recurrent cases 1
• Sialography: Reserved for recurrent parotitis to identify ductal abnormalities; may be therapeutic by flushing debris 6

Differential Diagnosis Considerations

Non-Infectious Causes

• Sjögren syndrome: Consider in patients with recurrent parotitis, especially with sicca symptoms 1
• Immune checkpoint inhibitor-related: Emerging cause in cancer patients on immunotherapy 1
• Sialolithiasis: Obstruction causing secondary inflammation 4, 7

Infectious Causes Beyond Mumps

• Other viruses: Epstein-Barr virus, coxsackievirus, influenza A, parainfluenza 4
• Mycobacterial: Rare but consider in immunocompromised patients or those with chronic symptoms 4, 5

Management Algorithm

Viral Parotitis

• Supportive care only: Hydration, analgesics, and isolation to prevent spread 1, 2
• Oral hygiene: Warm saline mouthwashes daily; antiseptic rinses with 0.2% chlorhexidine or 1.5% hydrogen peroxide twice daily 2
• Pain management ladder: Start with benzydamine hydrochloride oral rinse every 3 hours; escalate to viscous lidocaine 2% if inadequate; use systemic analgesics for severe pain 2
• Monitor for complications: Orchitis (up to 38% of postpubertal men), aseptic meningitis (4-6%), sensorineural deafness 1, 2, 3

Bacterial Suppurative Parotitis

• Empiric antimicrobial therapy: Must cover S. aureus and anaerobes, accounting for beta-lactamase production 4, 5
• Hydration: Aggressive IV fluids to promote salivary flow 4, 5
• Surgical drainage: Required once abscess forms; early intervention prevents complications 4, 5
• Adjust antibiotics: Based on culture results and clinical response 5

Recurrent/Chronic Parotitis

• Conservative management first: Expectant policy with hydration and oral hygiene, especially in children who typically improve by puberty 6
• Sialography: May be therapeutic by clearing ductal debris 6
• Surgical options: Reserved for adults with persistent symptoms—parotid duct ligation, parotidectomy, or tympanic neurectomy 6, 7

Critical Red Flags Requiring Urgent Referral

• Purulent discharge from Stensen's duct with systemic toxicity 4, 5
• Imaging evidence of abscess formation 1
• Failure to improve with 48-72 hours of appropriate antimicrobial therapy 5
• Complications such as facial nerve involvement or extension to deep neck spaces 8