What is the recommended treatment for acute mastoiditis, including antibiotic choices, dosing, duration, and indications for surgical drainage?

Treatment of Acute Mastoiditis

Initial Management: Start IV Antibiotics Immediately

Begin intravenous broad-spectrum antibiotics immediately upon diagnosis of acute mastoiditis, with cloxacillin/flucloxacillin (50 mg/kg QDS for children, 2g every 6 hours for adults) as first-line therapy, or ceftriaxone (50-80 mg/kg daily) as second-line. 1, 2

• Acute mastoiditis is a serious complication of acute otitis media requiring prompt aggressive treatment to prevent intracranial complications 1
• Pain management is critical and should be initiated alongside antibiotic therapy 1
• Consider myringotomy with or without tympanostomy tube insertion at initial presentation for drainage 1, 2

Antibiotic Selection and Dosing

First-Line Therapy

• Cloxacillin/flucloxacillin IV: 50 mg/kg every 6 hours (QDS) for children, 2g every 6 hours for adults, for 10 days 2
• This targets Streptococcus pneumoniae, which remains the most common pathogen despite PCV-13 vaccination 2, 3

Second-Line Therapy

• Ceftriaxone IV: 50-80 mg/kg daily (for penicillin allergy or treatment failure) 2, 3

Complicated Cases Requiring Broader Coverage

• For complicated mastoiditis with suspected polymicrobial infection or intracranial extension: Vancomycin PLUS one of the following: piperacillin-tazobactam, carbapenem, ceftriaxone plus metronidazole, or fluoroquinolone plus metronidazole 1
• For confirmed Streptococcus pyogenes: Add clindamycin to penicillin therapy 1

Important Pathogen Considerations

• Streptococcus pneumoniae is most common (28.57%), followed by Staphylococcus aureus (16.32%), Streptococcus pyogenes, Haemophilus influenzae, and Pseudomonas aeruginosa 2, 3, 4
• Cultures may be negative in 33-53% of cases, so empiric therapy is essential 2, 4

Reassessment at 48 Hours: The Critical Decision Point

Reassess all patients after 48 hours of IV antibiotics to determine need for surgical intervention. 1, 2

Indications for Surgery

Proceed to surgical intervention if ANY of the following are present:

• No clinical improvement after 48 hours of IV antibiotics 1, 2, 5
• Clinical deterioration at any point 1
• Development of complications (subperiosteal abscess, intracranial extension) 1, 2, 5
• Evidence of osteomyelitis beyond the mastoid framework 5

Surgical Options

• Myringotomy with or without tympanostomy tube: For uncomplicated cases with persistent effusion 1, 6, 7
• Cortical mastoidectomy: Standard approach for most complicated cases 1, 5
• Modified radical mastoidectomy: For extensive disease with osteomyelitis 5

Treatment Success Rates by Modality

Understanding these rates helps guide decision-making:

• Antibiotics alone: 10% success rate 1, 2
• Antibiotics plus myringotomy: 68% success rate 1, 2
• Antibiotics plus mastoidectomy: 22% success rate (reserved for complicated cases) 1, 2

Imaging Recommendations

When to Image

• Obtain CT temporal bone with IV contrast if patient fails to improve after 48 hours OR if clinical deterioration occurs at any point 1
• CT provides high spatial resolution for assessing bony erosion and intratemporal complications 1

Advanced Imaging for Suspected Complications

• MRI without and with IV contrast if intracranial complications are suspected (brain abscess, subdural empyema, meningitis, sigmoid sinus thrombosis) 1
• MRI has higher sensitivity and specificity than CT for detecting intracranial complications 1

Duration of Antibiotic Therapy

Standard Acute Mastoiditis

• IV antibiotics: 7-10 days, then transition to oral therapy based on clinical improvement 1, 5
• Total duration: 10 days for uncomplicated cases 2

Mastoiditis with Osteomyelitis

• IV antibiotics: 7-10 days post-surgery 5
• Total duration: 4-6 weeks for osteomyelitis 5

Transition to Oral Antibiotics

High-dose amoxicillin-clavulanate (80-90 mg/kg/day of amoxicillin component, divided twice daily, maximum 4000 mg/day for children; 2000 mg twice daily for adults) is the preferred oral step-down therapy. 1

Alternative Oral Options

• For non-immediate β-lactam hypersensitivity: Cefdinir, cefpodoxime proxetil, or cefuroxime axetil 1
• For immediate Type I β-lactam hypersensitivity: Clindamycin PLUS an agent covering H. influenzae and M. catarrhalis (cefixime or cefdinir) 1
• AVOID macrolides (azithromycin, clarithromycin) due to high failure rates (20-25%) from pneumococcal resistance 1
• AVOID trimethoprim-sulfamethoxazole due to substantial pneumococcal resistance 1

Critical Monitoring After Transition

• Reassess within 48-72 hours of switching to oral therapy to ensure continued improvement 1

Monitoring for Complications

Extracranial Complications

• Subperiosteal abscess (most common surgical indication) 1, 3
• Bezold's abscess 3

Intratemporal Complications

• Facial nerve palsy 3
• Labyrinthitis 3

Intracranial Complications (Most Serious)

• Brain abscess (most common intracranial complication) 1
• Sigmoid sinus thrombosis 1, 2
• Subdural empyema 1
• Meningitis 1, 7

Warning Signs Requiring Immediate Imaging

• Persistent fever or elevated inflammatory markers despite treatment 5
• Neurological signs: nuchal rigidity, altered consciousness, seizures, focal deficits 1
• No reliable clinical signs distinguish patients with intracranial complications, making imaging crucial in non-resolving cases 1

Follow-Up Care

• Hearing assessment should be performed if middle ear effusion persists for ≥3 months 1
• Persistent middle ear effusion is expected in 60-70% of children at 2 weeks, decreasing to 10-25% at 3 months, and does not require continued antibiotics unless symptomatic 1
• Regular follow-up is important to ensure complete resolution and monitor for recurrence 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, 4
• Do not delay imaging in non-responders: Obtain CT at 48 hours if no improvement, as intracranial complications can develop rapidly 1
• Do not use antibiotics alone as definitive therapy: Only 10% success rate; most patients require myringotomy at minimum 1, 2
• Do not use macrolides or TMP-SMX for step-down therapy: High resistance rates lead to treatment failure 1
• Do not assume persistent effusion requires continued antibiotics: This is expected and resolves over 3 months 1