What is the diagnosis and treatment for a 10-month-old infant with a 3-day history of rhinorrhea, fever, irritability, and decreased appetite, who also has a bulging and erythematous tympanic membrane with effusion in the right ear, lymphadenopathy, and is presenting with tachycardia, tachypnea, and hyperthermia?

Acute Otitis Media (AOM) with Right Ear Infection

This 10-month-old infant has acute otitis media (AOM) of the right ear and should be treated with high-dose amoxicillin (80-90 mg/kg/day divided twice daily) for 10 days, along with appropriate pain management. 1, 2

Diagnosis

The diagnosis of AOM is confirmed by the presence of:

• Moderate-to-severe bulging of the tympanic membrane (right ear shows bulging, erythematous, opaque tympanic membrane with effusion) 1
• Acute symptoms including fever (39.1°C), irritability, decreased appetite, and difficulty feeding 1, 2
• Recent onset (3-day history) following viral upper respiratory tract infection (rhinorrhea) 1, 3

The right submandibular lymphadenopathy is reactive and consistent with the infectious process. 1 The left ear shows only slight dullness without bulging or erythema, which does not meet criteria for AOM. 1

Treatment Approach

Antibiotic Therapy

High-dose amoxicillin is the first-line antibiotic for this patient: 1, 2

• Dosage: 80-90 mg/kg/day divided into two doses daily 1, 2
• Duration: 10 days (for children <2 years of age) 4
• Calculation: This infant weighs 20.7 lb (9.4 kg), requiring approximately 750-850 mg total daily dose, divided as 375-425 mg twice daily 5

The infant meets criteria for antibiotic treatment rather than watchful waiting because: 1

• Age <2 years with unilateral AOM
• Severe symptoms (temperature ≥39°C, moderate-to-severe bulging of tympanic membrane) 1

Pain Management

Symptomatic management of ear pain and fever is essential: 1

• Acetaminophen or ibuprofen for fever and pain control 1
• Pain management should be initiated immediately, regardless of antibiotic decision 1

Clinical Reasoning

Why Antibiotics Are Indicated

This case requires antibiotics rather than observation because: 1

• Severe AOM criteria met: Temperature ≥39°C (39.1°C measured) 1
• Age <2 years: Younger children have higher risk of complications and lower rates of spontaneous resolution 1, 2
• Bulging tympanic membrane: Strong predictor of bacterial infection requiring treatment 1

Alternative Antibiotics (If Needed)

If treatment fails after 48-72 hours or if penicillin allergy exists: 1

• First-line alternative: Amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component) 1
• Penicillin allergy: Cefdinir or azithromycin (though cephalosporins have only 0.1% cross-reactivity in non-severe penicillin allergy) 1, 2
• Treatment failure: Consider intramuscular ceftriaxone (50 mg/kg) if oral therapy fails 1

Follow-Up and Monitoring

Clinical improvement should occur within 48-72 hours: 1

• Temperature should decline within 48-72 hours 1
• Irritability and feeding patterns should normalize 1
• If no improvement by 48-72 hours, consider treatment failure and change antibiotics 1

Important note: The infant does not require routine follow-up otoscopy if symptoms resolve, but parents should be counseled to return if symptoms persist or worsen. 1

Common Pitfalls to Avoid

Do not diagnose AOM based on erythema alone - the tympanic membrane must be bulging, as erythema can result from crying or viral infection without bacterial AOM. 1, 6 This infant has clear bulging documented, confirming the diagnosis.

Do not use ototoxic topical antibiotics - there is no indication for topical therapy in this case, but if tympanic membrane perforation occurs, only non-ototoxic preparations should be used. 4

Do not confuse with otitis media with effusion (OME) - OME presents without acute symptoms or bulging and does not require antibiotics. 1, 4 This infant has clear acute inflammatory signs.

Concurrent Viral Upper Respiratory Infection

The preceding viral URI (rhinorrhea, clear nasal discharge) is typical, as 37% of children develop AOM following viral URTI. 1 The viral infection causes Eustachian tube dysfunction, allowing bacterial pathogens from the nasopharynx to ascend into the middle ear. 1, 3 This does not change management but explains the clinical presentation.