What causes parotid gland infection?

Causes of Parotid Gland Infection

Parotid gland infections are most commonly caused by viral pathogens (especially mumps virus) and bacterial organisms (predominantly Staphylococcus aureus), with predisposing factors including dehydration, ductal obstruction, and reduced salivary flow.

Viral Causes

Mumps Virus (Paramyxovirus)

• Most classic viral cause of parotid inflammation
• Presents with bilateral parotid swelling, fever, headache, nausea, and vomiting 1
• Diagnosis confirmed by:
  • PCR of parotid (Stensen) duct/buccal swab (most accurate)
  • Viral culture from parotid gland duct swabs after massaging the parotid gland for 30 seconds 1
  • Serology for mumps-specific IgM antibodies
• Can lead to complications including orchitis in post-pubertal males 1

Other Viral Causes

• Epstein-Barr virus (EBV) - can present as follicular conjunctivitis with ipsilateral lymphadenopathy 1
• Coxsackievirus
• Influenza A virus
• Parainfluenza viruses 2

Bacterial Causes

Common Bacterial Pathogens

• Staphylococcus aureus - most common bacterial cause 3, 4
• Streptococcus species (including S. pneumoniae)
• Anaerobic bacteria:
  • Peptostreptococcus species
  • Bacteroides species
  • Pigmented Prevotella and Porphyromonas species 2, 3
  • Fusobacterium species 4

Less Common Bacterial Pathogens

• Gram-negative bacilli (especially in hospitalized patients):
  • Escherichia coli
  • Klebsiella pneumoniae
  • Pseudomonas aeruginosa
• Haemophilus influenzae
• Salmonella species 3
• Mycobacterium tuberculosis and atypical mycobacteria (rare) 4, 5

Predisposing Factors

Factors Promoting Bacterial Infection

• Dehydration - most significant factor
• Malnutrition
• Medications that reduce salivation (xerogenic drugs)
• Sialolithiasis (salivary stones)
• Ductal obstruction
• Poor oral hygiene
• Immunosuppression
• Oral neoplasms 2, 5

Risk Factors for Viral Infection

• Lack of vaccination (for mumps)
• Close contact with infected individuals
• Participation in organized sports or other group activities 1

Diagnostic Approach

For Bacterial Parotitis

• Aspiration of pus from suppurative parotid abscess
• Culture on media supporting aerobic and anaerobic bacteria, mycobacteria, and fungi 2
• Blood cultures (preferred over direct swabbing) 6

For Viral Parotitis (Mumps)

• Parotid (Stensen) duct/buccal swab for viral culture or PCR
• Serology for virus-specific antibodies
• Urine samples (less sensitive than oral specimens) 1

Management Considerations

Bacterial Parotitis

• Hydration maintenance
• Parenteral antimicrobial therapy targeting both aerobic and anaerobic bacteria
• Surgical drainage if abscess has formed 3
• Antimicrobial selection guided by culture and sensitivity results

Viral Parotitis

• Supportive care
• Hydration
• Pain management
• Prevention through vaccination (for mumps) 1

Understanding the specific cause of parotid gland infection is essential for appropriate management and prevention of complications such as abscess formation, facial nerve involvement, and systemic spread of infection.