Oral Antibiotic Selection for Chronic Suppurative Otitis Media
For chronic suppurative otitis media (CSOM), topical ofloxacin 0.3% otic solution is the treatment of choice, NOT oral antibiotics. If you must use an oral antibiotic, the evidence suggests oral ciprofloxacin or amoxicillin, though systemic antibiotics alone show very limited efficacy for CSOM 1.
Critical Distinction: CSOM is NOT Acute Otitis Media
- Chronic suppurative otitis media is fundamentally different from acute otitis media and requires a different treatment approach 2
- CSOM is defined as chronic ear discharge through a perforated tympanic membrane, typically lasting more than 2 weeks 2, 1
- The pathogens in CSOM differ from acute otitis media: predominantly Staphylococcus aureus (30%), Pseudomonas aeruginosa (25%), and Proteus mirabilis 3, 4
- Guidelines for acute otitis media (which recommend amoxicillin or amoxicillin-clavulanate) do NOT apply to CSOM 2
Recommended Treatment Approach
First-Line: Topical Therapy (NOT Oral)
Ofloxacin 0.3% otic solution is the evidence-based first-line treatment:
- Dosing: 0.5 mL (approximately 10 drops) instilled twice daily for 14 days 5, 3
- Clinical cure rate: 91% in patients ≥12 years with CSOM 3
- FDA-approved specifically for CSOM with perforated tympanic membranes in patients ≥12 years 5
- Provides excellent coverage against Pseudomonas aeruginosa and Staphylococcus aureus, the primary CSOM pathogens 3, 6
- Significantly superior to oral amoxicillin plus topical chloramphenicol (cure rate 91% vs 67%, p<0.001) 4
If Oral Antibiotics Must Be Used
The evidence for oral antibiotics in CSOM is very weak, but if required:
- Oral ciprofloxacin is the most studied systemic option, though it shows little or no benefit when added to topical therapy 1
- When used alone (without topical therapy), systemic antibiotics have very uncertain efficacy compared to placebo 1
- One study showed oral amoxicillin 500 mg three times daily had inferior results compared to topical ofloxacin 4
Important Clinical Considerations
Common pitfalls to avoid:
- Do NOT treat CSOM with the same antibiotics used for acute otitis media (amoxicillin-clavulanate, cefuroxime) - these target different pathogens 2
- Do NOT use aminoglycoside ear drops (neomycin, gentamicin) in patients with perforated tympanic membranes due to ototoxicity risk 5, 4
- Chloramphenicol ear drops showed significantly higher ototoxicity rates compared to ofloxacin (p<0.001) 4
Administration technique for topical ofloxacin:
- Warm the bottle in hand for 1-2 minutes before instillation to avoid dizziness 5
- Patient should lie with affected ear upward 5
- After instillation, pump the tragus 4 times to facilitate middle ear penetration 5
- Maintain position for 5 minutes 5
When to Reassess or Escalate
- If no improvement after one week of topical therapy, obtain cultures to guide further treatment 5
- Consider underlying conditions (cholesteatoma, foreign body, tumor) if otorrhea persists after full 14-day course 5
- Refer to ENT if two or more episodes occur within 6 months 5
Evidence Quality Summary
The evidence strongly favors topical fluoroquinolones over systemic antibiotics for CSOM. A 2025 Cochrane review found very low-certainty evidence that systemic antibiotics provide benefit, whether used alone or added to topical therapy 1. In contrast, topical ofloxacin demonstrated 91% clinical cure rates in well-designed trials 3, 6.