What antibiotic will cover mastitis and otitis media?

Antibiotic Coverage for Mastitis and Otitis Media

High-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin with 6.4 mg/kg/day of clavulanate in 2 divided doses) provides optimal coverage for both mastitis and otitis media, as it effectively targets the overlapping bacterial pathogens including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, and Streptococcus pyogenes. 1, 2, 3

Rationale for Amoxicillin-Clavulanate

Coverage for Otitis Media Pathogens

• High-dose amoxicillin-clavulanate is specifically recommended by the American Academy of Pediatrics for acute otitis media when coverage for β-lactamase-producing organisms (H. influenzae and M. catarrhalis) is needed 1, 2
• This formulation achieves middle ear fluid levels exceeding the minimum inhibitory concentration for penicillin-intermediate and many penicillin-resistant S. pneumoniae strains 1
• The 14:1 ratio of amoxicillin to clavulanate (90/6.4 mg/kg/day) minimizes diarrhea while maintaining efficacy against resistant pathogens 1, 4

Coverage for Mastoiditis Pathogens

• Streptococcus pneumoniae remains the most common causative organism in mastoiditis, with other key pathogens including S. pyogenes, S. aureus, H. influenzae, and Pseudomonas aeruginosa 3
• While cloxacillin/flucloxacillin (50 mg/kg QDS IV) is recommended as first-line for acute mastoiditis in the emergency department, amoxicillin-clavulanate provides broader coverage when both conditions need to be addressed 3

Alternative Regimen: Ceftriaxone

For patients requiring parenteral therapy or with penicillin allergy (non-severe), ceftriaxone (50-80 mg/kg/day IV) serves as an excellent alternative covering both conditions. 2, 3, 5

Advantages of Ceftriaxone

• FDA-approved for acute bacterial otitis media caused by S. pneumoniae, H. influenzae (including β-lactamase producing strains), and M. catarrhalis 5
• Recommended as second-line therapy for mastoiditis by the American Academy of Otolaryngology-Head and Neck Surgery 3
• Can be administered as 50 mg IM or IV per day for 1-3 days for otitis media treatment failures 2

Clinical Algorithm

For Oral Therapy (Outpatient):

1. First-line: High-dose amoxicillin-clavulanate (90/6.4 mg/kg/day divided BID) 1, 2
2. If penicillin allergy: Cefdinir (14 mg/kg/day), cefuroxime (30 mg/kg/day), or cefpodoxime (10 mg/kg/day) 2
3. Duration: 10 days for children <2 years; 7 days for ages 2-5 years with mild-moderate symptoms 2

For Parenteral Therapy (Inpatient/Severe):

1. Mastoiditis-predominant: IV cloxacillin/flucloxacillin (50 mg/kg QDS) or ceftriaxone (50-80 mg/kg/day) 3
2. Reassess at 48 hours: If no improvement, consider surgical intervention (myringotomy, mastoidectomy) 3

Important Clinical Caveats

Resistance Considerations

• Approximately 58-82% of H. influenzae isolates produce β-lactamase, necessitating the clavulanate component 1
• Current data show 83-87% of S. pneumoniae isolates are susceptible to high-dose amoxicillin 1
• Prior antibiotic use does not prevent mastoiditis development (33-81% of mastoiditis patients had received prior antibiotics) 2, 3

Treatment Failure Management

• If symptoms worsen or fail to improve within 48-72 hours on amoxicillin-clavulanate, switch to ceftriaxone (50 mg/kg/day IM/IV for 1-3 days) 2
• For mastoiditis without improvement after 48 hours of IV antibiotics, obtain CT imaging and consider surgical intervention 3

Pitfalls to Avoid

• Do not use topical antibiotics for mastoiditis or suppurative otitis media, as these are contraindicated 2
• Do not use corticosteroids routinely for acute otitis media, as evidence does not support their effectiveness 2
• Do not delay antibiotics in children <6 months with otitis media or in any patient with suspected mastoiditis 2, 3