What antibiotics are recommended for the treatment of parotitis?

Antibiotics for Parotitis

For acute bacterial suppurative parotitis, initiate empiric therapy with an anti-staphylococcal agent (such as cloxacillin or oxacillin) combined with anaerobic coverage (clindamycin or metronidazole), or use a single agent with broad coverage such as amoxicillin-clavulanate.

Microbiology of Bacterial Parotitis

The pathogen profile in acute bacterial parotitis differs significantly from other head and neck infections:

• Staphylococcus aureus remains the most common pathogen in acute suppurative parotitis 1, 2
• Anaerobic bacteria play a major pathogenic role and are increasingly recognized, including:
  • Gram-negative bacilli (Prevotella and Porphyromonas species) 1
  • Fusobacterium species 1, 3
  • Peptostreptococcus species 1, 3
• Streptococcus species (including S. pneumoniae) are also implicated 1
• Gram-negative facultative organisms (E. coli, Klebsiella, Pseudomonas) are particularly common in hospitalized patients 1
• Less common organisms include Eikenella corrodens, Haemophilus influenzae, and Salmonella species 1, 4

Initial Empiric Antibiotic Therapy

For Moderately Ill Patients

• Amoxicillin-clavulanate provides coverage for S. aureus, streptococci, and anaerobes in a single agent
• Cloxacillin alone if anaerobic infection is less likely (early presentation, good oral hygiene) 2

For Severely Ill or Hospitalized Patients

• Cloxacillin (or oxacillin) PLUS an aminoglycoside for initial coverage of S. aureus and gram-negative facultative organisms 2
• Add clindamycin or penicillin if there is failure to respond clinically within 48-72 hours, or if anaerobic bacteria are isolated 2

Important Clinical Considerations

Anaerobic bacteria may be present in high concentrations (>5 × 10⁶ CFU/ml) and can be the sole pathogens in some cases 3. A critical finding is that some Fusobacterium strains show resistance to penicillin, amoxicillin, and erythromycin but remain sensitive to metronidazole 3.

When to Suspect Abscess Formation

Consider parotid abscess (requiring surgical drainage) when patients present with:

• Subacute presentation (approximately 10 days of symptoms) 5
• Fluctuation on palpation 5
• Normal hemoglobin levels (>12-13 g/dL) 5

Surgical Management

Once an abscess has formed, surgical drainage is required in addition to antimicrobial therapy 1. Small vertical skin incision over the well-localized abscess pocket achieves good results without requiring formal parotidectomy incision 5.

Antibiotic Selection Algorithm

1. Initial therapy: Start with anti-staphylococcal coverage (cloxacillin/oxacillin) 2
2. If severely ill: Add aminoglycoside for gram-negative coverage 2
3. If no clinical response in 48-72 hours: Add anaerobic coverage with clindamycin or metronidazole 2
4. If anaerobes isolated: Ensure antibiotic sensitivity testing is performed, as resistance patterns vary 3

Supportive Measures

Essential adjunctive therapy includes:

• Maintenance of adequate hydration 1
• Good oral hygiene 1
• Parenteral administration for moderate-to-severe disease 5

Common Pitfall

Do not rely solely on standard penicillin or amoxicillin monotherapy, as these agents lack adequate coverage for S. aureus (the most common pathogen) and may not cover resistant anaerobes 1, 3. The addition of a beta-lactamase inhibitor (clavulanate) or use of anti-staphylococcal penicillins is essential.