What is the appropriate diagnosis and first‑line treatment for an adult presenting with a retracted, erythematous, bulging tympanic membrane and middle‑ear fluid?

Diagnosis and First-Line Treatment for Adult Acute Otitis Media

The diagnosis is acute otitis media (AOM), and the first-line treatment is high-dose amoxicillin (80–90 mg/kg/day in adults, typically 1000 mg three times daily or 875 mg twice daily). 1, 2

Diagnostic Criteria

AOM requires three essential elements to be present simultaneously:

• Acute onset of symptoms (rapid development of ear pain, fever, or irritability) 3, 4
• Middle ear effusion documented by bulging tympanic membrane, limited/absent tympanic membrane mobility, air-fluid level, or otorrhea 3, 4
• Signs of middle ear inflammation indicated by distinct erythema of the tympanic membrane combined with bulging or fullness 3, 4

Key Otoscopic Findings in This Case

The presentation of a "deflated" (retracted), red, fluid-filled tympanic membrane requires careful interpretation:

• A bulging tympanic membrane is the most predictive finding for AOM (specificity ~96%), not a retracted one 4, 5
• Retraction typically indicates negative middle ear pressure (eustachian tube dysfunction) or otitis media with effusion (OME), not acute infection 4, 5
• However, if distinct erythema and fluid are present together with acute symptoms, this meets AOM criteria even if the membrane position is ambiguous 3, 4
• The combination of redness, fluid, and acute symptoms in an adult strongly suggests AOM requiring antibiotic therapy 1, 6

Critical Diagnostic Pitfall

Do not confuse AOM with otitis media with effusion (OME):

• OME presents with middle ear fluid but lacks acute inflammatory signs (no distinct erythema, no acute pain, no fever) 3, 5
• OME does not require antibiotics, whereas AOM does 3, 2
• The key differentiating feature is tympanic membrane position and inflammation: bulging with distinct erythema indicates AOM; neutral or retracted position without acute inflammation indicates OME 5, 2
• Mistaking OME for AOM leads to unnecessary antibiotic prescriptions 3, 4

Pneumatic Otoscopy Confirmation

Perform pneumatic otoscopy to assess tympanic membrane mobility:

• Limited or absent mobility confirms middle ear effusion 3, 4
• This technique is essential because symptoms alone are poorly predictive (fever and ear pain are present in only 50% of AOM cases) 4, 5

First-Line Antibiotic Treatment

Amoxicillin is the first-line antibiotic for uncomplicated AOM in adults:

• Dosing: High-dose amoxicillin (80–90 mg/kg/day, typically 1000 mg three times daily or 875 mg twice daily in adults) 1, 2
• Rationale: Amoxicillin covers the most common bacterial pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis) 7, 8, 2
• Duration: Typically 5–10 days, though exact duration should be based on clinical response 2

Alternative Regimens for Penicillin Allergy

For penicillin-allergic patients:

• First-generation cephalosporin, clindamycin, or clarithromycin for 10 days 1
• Azithromycin for 5 days 1

Pain Management

Address pain immediately, regardless of antibiotic use:

• Recommend NSAIDs (ibuprofen) or acetaminophen for analgesia 1, 2
• Pain management should be initiated within the first 24 hours 3

Monitoring and Follow-Up

Reassess if symptoms do not improve within 48–72 hours:

• Persistent symptoms warrant reexamination and consideration of second-line therapy (amoxicillin-clavulanate) 1, 2
• Watch for complications: new-onset headache, vertigo, meningismus, or focal neurological deficits may indicate intracranial extension 9

Common Clinical Pitfalls to Avoid

• Do not rely on tympanic membrane erythema alone—redness from crying or viral URI is insufficient without bulging and effusion 4, 5
• Do not prescribe antibiotics without adequate visualization of the tympanic membrane 4
• Ensure adequate light source and cerumen removal to avoid diagnostic errors 5
• If the membrane is truly retracted (not bulging) and symptoms are mild, consider observation or reevaluation for OME rather than immediate antibiotics 5, 2