What are the recommended antibiotics for treating mastoiditis?

Antibiotic Treatment for Mastoiditis

Initiate intravenous broad-spectrum antibiotics immediately upon diagnosis of mastoiditis, with cloxacillin/flucloxacillin (50 mg/kg QDS, or 2g every 6 hours in adults) as first-line therapy, or ceftriaxone (50-80 mg/kg daily) as second-line, combined with early myringotomy consideration and reassessment at 48 hours. 1, 2

Initial Antibiotic Selection

First-Line Therapy

• Cloxacillin/flucloxacillin IV is the recommended first-line antibiotic for mastoiditis 2
  • Pediatric dosing: 50 mg/kg every 6 hours (QDS) for 10 days 2
  • Adult dosing: 2g every 6 hours IV 2

Second-Line Therapy

• Ceftriaxone IV is the second-line option 2
  • Dosing: 50-80 mg/kg daily 2
  • This choice is supported by the predominance of Streptococcus pneumoniae as the causative organism 3, 4, 5

Complicated or Severe Cases

• For complicated mastoiditis (with intracranial complications, subperiosteal abscess, or clinical deterioration), broader coverage is warranted 1
• The American Academy of Otolaryngology-Head and Neck Surgery recommends vancomycin plus one of the following 1:
  • Piperacillin-tazobactam
  • A carbapenem
  • Ceftriaxone plus metronidazole
  • A fluoroquinolone plus metronidazole

Bacteriology Considerations

Common Pathogens

• Streptococcus pneumoniae remains the most common causative organism despite PCV-13 vaccination 3, 4, 6, 5
• Other important pathogens include Streptococcus pyogenes, Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa 4, 5
• Mixed flora occurs in some cases, requiring broader coverage 4, 5

Culture-Negative Cases

• Cultures may be negative in 33-53% of cases, emphasizing the importance of empiric therapy 2, 5
• When cultures are positive, antibiotic choices should be adjusted accordingly 1

Treatment Algorithm

Initial Management (0-48 hours)

• Start IV antibiotics immediately upon diagnosis 1, 2
• Consider myringotomy with or without tympanostomy tube insertion for drainage 1, 2
• Provide appropriate pain management 3, 1

Reassessment at 48 Hours

• If improving: Continue IV antibiotics and consider transition to oral therapy once clinical improvement is noted 1
• If not improving or worsening: 1, 2
  • Obtain CT scan to identify complications
  • Consider surgical intervention (mastoidectomy)
  • Broaden antibiotic coverage if not already done

Duration of Therapy

• Total duration: 10 days of antibiotic therapy 2
• Transition to oral antibiotics may be considered once clinical improvement is documented 1

Special Considerations

Confirmed Streptococcus pyogenes

• Add clindamycin to penicillin therapy for confirmed S. pyogenes cases 1

Failed Initial Therapy

• Adjust antibiotics based on culture results when available 1
• Consider clindamycin with or without coverage for H. influenzae and Moraxella catarrhalis 1

Critical Pitfalls to Avoid

Prior Antibiotic Treatment Does Not Prevent Mastoiditis

• 33-81% of patients with acute mastoiditis had received antibiotics before admission 1, 2, 5, 7
• This means outpatient oral antibiotics for acute otitis media do not reliably prevent progression to mastoiditis 5, 7
• Do not delay IV antibiotics based on recent oral antibiotic use 1, 2

Imaging Indications

• Obtain CT scan if: 1
  • No improvement after 48 hours of IV antibiotics
  • Clinical deterioration at any point
  • Suspicion of intracranial complications (brain abscess, sigmoid sinus thrombosis)

Surgical Intervention Thresholds

• Mastoidectomy rates vary widely (29-93%) in contemporary series, reflecting practice variation rather than disease severity 3
• Success rates by treatment modality: 1, 2
  • Antibiotics alone: 10%
  • Antibiotics plus myringotomy: 68%
  • Antibiotics plus mastoidectomy: 22%
• Consider surgery if: 1, 2
  • No improvement after 48 hours of IV antibiotics
  • Development of complications
  • Presence of subperiosteal abscess (though needle aspiration may be attempted first) 3

Follow-Up Care

Monitoring

• Regular follow-up is essential to ensure complete resolution and monitor for complications 1
• Persistent middle ear effusion is common after resolution of acute symptoms 1
• Hearing assessment should be performed if effusion persists for ≥3 months 1