What is the best course of treatment for a 2-year-old male patient with suspected acute mastoiditis, initially treated with ceftriaxone (a third-generation cephalosporin) and then switched to Unasyn (ampicillin-sulbactam)?

Treatment of Acute Mastoiditis in a 2-Year-Old After Initial Ceftriaxone and Unasyn Therapy

Continue IV antibiotics with either ceftriaxone or ampicillin-sulbactam (Unasyn) combined with myringotomy, and reserve mastoidectomy only for cases with subperiosteal abscess, failure to improve after 48 hours of IV therapy, or suspected cholesteatoma. 1, 2

Initial Assessment and Treatment Strategy

The switch from ceftriaxone to Unasyn (or vice versa) is clinically appropriate and requires no washout period, as both are beta-lactam antibiotics with compatible mechanisms of action. 3 However, the key question is whether conservative management alone will suffice or if surgical intervention is needed.

Conservative Management Approach

Medical therapy with IV antibiotics achieves cure rates of 95.9% in uncomplicated acute mastoiditis cases. 2 The treatment algorithm should proceed as follows:

• Initiate or continue IV antibiotics immediately - either ceftriaxone 50-100 mg/kg/day (given the child's age of 2 years and severity of mastoiditis, use the higher end: 80-100 mg/kg/day) or continue ampicillin-sulbactam. 1, 4, 3

• Perform wide myringotomy with or without tympanostomy tube insertion as the primary surgical intervention in 68-86% of pediatric acute mastoiditis cases. 1, 5 This combined with IV antibiotics successfully treats the majority of cases without requiring mastoidectomy. 6, 7

• Assess daily for clinical response - improvement should be evident within 48 hours of appropriate IV antibiotic therapy. 1, 5

Indications for Mastoidectomy

Proceed to cortical mastoidectomy only if:

• Subperiosteal abscess is present - this is the most common indication, occurring in approximately 22-32% of cases. 1, 6, 7 Note that needle aspiration combined with myringotomy may be attempted first in selected cases before proceeding to mastoidectomy. 1

• Failure to improve after 48 hours of IV antibiotics and myringotomy, or clinical deterioration at any time. 1, 8

• Cholesteatoma is clinically suspected - this was found in 3 of 4 children who underwent mastoidectomy in one series. 7

• Intracranial complications are present (neurologic deficits, sepsis, or imaging evidence of intracranial extension). 1

Antibiotic Selection Rationale

Streptococcus pneumoniae remains the most common causative organism globally, though Streptococcus pyogenes is also frequently identified. 1, 8

• Ceftriaxone provides excellent coverage for S. pneumoniae including penicillin-resistant strains at 100 mg/kg/day. 4 For a 2-year-old with acute mastoiditis, dosing should be 80-100 mg/kg/day divided every 12-24 hours. 4

• Ampicillin-sulbactam (Unasyn) provides broader coverage including anaerobes and beta-lactamase producing organisms. 3 The switch to Unasyn may have been made to broaden coverage if initial response to ceftriaxone was inadequate. 3

• If switching back to ceftriaxone from Unasyn, ensure adequate anaerobic coverage is not needed; if anaerobes are suspected, add metronidazole. 3

Critical Management Pitfalls to Avoid

• Do not delay surgical consultation beyond 48 hours if the patient fails to improve on appropriate IV antibiotics, as this increases risk of intracranial complications. 1, 8

• Do not routinely perform mastoidectomy in all cases - contemporary data shows only 22-29% require this procedure, with the majority successfully managed conservatively. 1, 2

• Do not use low-dose ceftriaxone (50 mg/kg/day) for acute mastoiditis - this is a severe infection requiring 80-100 mg/kg/day for adequate tissue penetration. 4

• Do not assume prior antibiotic therapy eliminates mastoiditis risk - 33-81% of children with acute mastoiditis had received antibiotics for acute otitis media prior to developing this complication. 1

Monitoring and Follow-up

Daily clinical assessment is essential during the first 48-72 hours of treatment, evaluating for:

• Resolution of fever and systemic symptoms 8, 5
• Improvement in retroauricular swelling, erythema, and tenderness 5
• Normalization of inflammatory markers (CRP, WBC) 8
• Absence of neurologic signs suggesting intracranial extension 1

CT imaging should be obtained if the patient fails to improve after 48 hours or shows clinical deterioration, to assess for intracranial complications or subperiosteal abscess requiring drainage. 1