What are the differential diagnoses and treatment options for a patient presenting with ear discharge?

Differential Diagnosis of Ear Discharge

The primary differential diagnoses for ear discharge are acute otitis externa (swimmer's ear), acute otitis media with tympanic membrane perforation, chronic suppurative otitis media, and otorrhea through tympanostomy tubes—each distinguished by specific examination findings that determine whether topical quinolone antibiotics alone or combined systemic therapy is required. 1, 2

Immediate Diagnostic Approach

Perform tragal/pinna manipulation first: Positive tenderness indicates otitis externa, while absence of manipulation tenderness points to middle ear pathology (AOM with perforation, CSOM, or tube otorrhea). 2

Otoscopic examination findings:

• Otitis externa: Ear canal edema, erythema, wet debris, and normal tympanic membrane mobility on pneumatic otoscopy (if visible through debris). 1, 3
• AOM with perforation: Bulging, erythematous tympanic membrane with visible perforation and purulent discharge; reduced or absent mobility on pneumatic otoscopy. 2
• Chronic suppurative otitis media: Persistent discharge ≥2 weeks through a non-intact tympanic membrane, often with tympanic membrane abnormalities including perforation. 1, 2
• Tube otorrhea: Visible tympanostomy tube with purulent drainage; most common sequela affecting 26-83% of children with tubes. 1

Critical pitfall: Failing to adequately visualize the tympanic membrane due to canal debris can lead to missed middle ear pathology—perform aural toilet with microsuction, gentle dry mopping, or irrigation before declaring the examination complete. 2

Microbiology by Diagnosis

Otitis externa pathogens: Pseudomonas aeruginosa (most common) and Staphylococcus aureus. 1, 3, 4

AOM with perforation pathogens: Streptococcus pneumoniae, Haemophilus influenzae (nontypeable), and Moraxella catarrhalis. 2

Tube otorrhea pathogens: Pseudomonas aeruginosa or typical nasopharyngeal pathogens (S. pneumoniae, H. influenzae, M. catarrhalis); suspect MRSA when discharge is recurrent or recalcitrant. 1

Fungal causes: Candida species is the most common fungal cause of ear discharge, particularly with prolonged or frequent quinolone use. 1, 4

Treatment Algorithm

For Otitis Externa (Intact Tympanic Membrane)

First-line: Topical quinolone drops (ciprofloxacin 0.2% or ofloxacin 0.3%) twice daily for 7 days. 5, 3

Dosing specifics:

• Ciprofloxacin 0.2%: 0.25 mL (entire single-dose container) twice daily, 12 hours apart. 3
• Ofloxacin 0.3%: Age ≥13 years: 10 drops once daily; age 6 months to <13 years: 5 drops once daily. 5

Add topical corticosteroid combination for significant canal swelling. 2

Acetaminophen or NSAIDs for pain management. 2

For AOM with Perforation or CSOM

First-line: Non-ototoxic topical quinolone drops (ofloxacin 0.3%) to avoid ototoxicity from aminoglycosides. 2, 5

Dosing for middle ear disease:

• Age ≥12 years: 10 drops twice daily (12 hours apart). 5
• Age 1 to <12 years: 5 drops twice daily. 5

Consider systemic antibiotics (amoxicillin or amoxicillin-clavulanate) based on severity, age <2 years, bilateral disease, or systemic symptoms (fever, severe otalgia). 2, 6

Clinical significance: Children with AOM presenting with ear discharge have proven bacterial infection in 58% of cases, higher axillary temperature, elevated pulse rate, and increased Yale scores compared to those without discharge—they are sicker and warrant antibiotic treatment. 6

For Tube Otorrhea

First-line: Topical quinolone drops with or without corticosteroid are superior to oral antibiotics, achieving 77-96% clinical cure versus 30-67% with systemic therapy. 1

Mechanism of superiority: Increased drug concentration at infection site and improved coverage of P. aeruginosa. 1

Dosing:

• Age ≥12 years: 10 drops twice daily. 1
• Age 1 to <12 years: 5 drops twice daily. 1

Limit topical therapy to a single course of no more than 10 days to prevent otomycosis. 1

Avoid systemic antibiotics as they provide inferior outcomes and cause adverse events (dermatitis, allergic reactions, GI upset, oral thrush, increased antibiotic resistance). 1

Critical technique: Clean ear canal of debris before administering drops by blotting the canal opening or using an infant nasal aspirator to gently suction visible secretions—this ensures drops reach the middle ear space. 1

For Concurrent Middle Ear and External Canal Disease

Patients with tympanostomy tubes or pre-existing perforations can develop diffuse otitis externa when purulent middle-ear secretions enter the external canal—this may require both topical quinolone drops AND systemic antibiotics. 2

Special Considerations

Contraindications to aminoglycoside drops: Never use aminoglycoside-containing eardrops (commonly used for otitis externa) in patients with non-intact tympanic membranes due to ototoxicity risk—only quinolone drops are approved. 1, 2

Age restrictions for ofloxacin:

• Ear canal infection: ≥6 months. 5
• Middle ear infection with tube: ≥1 year. 5
• Middle ear infection with perforation: ≥12 years. 5

Warming drops: Hold bottle in hand for 1-2 minutes before instillation to minimize dizziness from cold solution. 5, 3

Proper instillation technique:

• Patient lies with affected ear upward. 5, 3
• For middle ear disease: Press tragus 4 times in pumping motion after instillation to allow drops to pass through perforation/tube. 1
• For ear canal infection: Pull outer ear upward and backward to straighten canal. 5
• Maintain position for at least 1-5 minutes. 5, 3

Red Flags Requiring Further Evaluation

Referred otalgia (normal ear examination): Consider temporomandibular joint syndrome (most common), pharyngitis, dental disease, cervical spine arthritis, or upper aerodigestive tract malignancy—especially in patients >50 years, tobacco/alcohol users, or diabetics. 1, 7

Herpes zoster oticus (Ramsay Hunt syndrome): Vesicles on external canal and posterior auricle, severe otalgia, facial paralysis, loss of taste, decreased lacrimation—requires prompt systemic antiviral therapy and steroids. 1

Cholesteatoma: Typically painless otorrhea with tympanic membrane abnormalities including perforation—requires ENT referral. 1

Lack of clinical response after 1 week: Obtain cultures to guide further treatment. 3