What antibiotics are recommended for the treatment of mastoiditis?

Antibiotic Treatment for Mastoiditis

The first-line antibiotic treatment for mastoiditis is intravenous cloxacillin/flucloxacillin at a dose of 2g every 6 hours for adults (50 mg/kg QDS for children), with ceftriaxone as a second-line option. 1

Microbiology and Pathogen Considerations

• The most common pathogens in mastoiditis are Streptococcus pneumoniae (51%), followed by Streptococcus pyogenes (11.5%), anaerobes (6.5%), and Staphylococcus aureus 2
• Haemophilus influenzae is also a significant pathogen, especially in pediatric populations 3, 4
• Pseudomonas aeruginosa may be present but is often considered a contaminant or concurrent infection 3

Initial Antibiotic Therapy

• Begin with broad-spectrum intravenous antibiotics immediately upon diagnosis 5, 1
• First-line therapy: IV cloxacillin/flucloxacillin at 2g every 6 hours for adults or 50 mg/kg QDS for children 1
• Second-line therapy: IV ceftriaxone at 50-80 mg/kg daily 1
• Third-generation cephalosporins are particularly effective against Streptococcus pneumoniae, the most common pathogen 3, 2

Treatment Algorithm

Uncomplicated Mastoiditis

• Start IV antibiotics immediately upon diagnosis 5, 1
• Consider myringotomy with or without tympanostomy tube insertion for drainage 5
• Reassess after 48 hours of IV antibiotic therapy 5, 1

If No Improvement After 48 Hours

• Obtain CT scan to identify potential complications 5
• Consider surgical intervention (mastoidectomy) 5, 2
• Adjust antibiotics based on culture results when available 5

For Complicated Mastoiditis

• Broader antibiotic coverage may be needed 5
• Consider vancomycin plus one of the following options for polymicrobial coverage: 6
  • Piperacillin-tazobactam
  • A carbapenem (imipenem-cilastatin, meropenem, or ertapenem)
  • Ceftriaxone plus metronidazole
  • A fluoroquinolone plus metronidazole

Duration of Therapy

• Continue IV antibiotics until clinical improvement is noted 5
• Transition to oral antibiotics once improvement is observed 5
• Total antibiotic course typically lasts 10-14 days 1

Special Considerations

• Prior antibiotic treatment does not prevent the development of mastoiditis, with 33-81% of patients diagnosed with acute mastoiditis having received antibiotics before admission 1, 7
• Cultures from mastoid infections may be negative in up to 33-53% of cases, emphasizing the importance of clinical diagnosis 1, 7
• Treatment success rates vary: antibiotics alone (10%), antibiotics plus myringotomy (68%), and antibiotics plus mastoidectomy (22%) 1, 8
• For cases with confirmed Streptococcus pyogenes (Group A Strep), consider adding clindamycin to penicillin therapy 6

Monitoring for Complications

• Watch for signs of intracranial complications, particularly sigmoid sinus thrombosis (3.2% of cases) 2
• Regular follow-up is essential to ensure complete resolution and monitor for recurrence 5
• Persistent middle ear effusion is common after resolution of acute symptoms and should be monitored 5
• Hearing assessment should be performed if effusion persists for ≥3 months 5

Surgical Indications

• Failure to improve after 48 hours of appropriate IV antibiotics 5, 2
• Development of complications 5
• Presence of subperiosteal abscess 5, 4
• Surgical failures are more frequent with anaerobes or gram-negative bacteria, suggesting broader antibiotic coverage may be needed in these cases 2