What is the recommended treatment for an ongoing sinus infection in an adult weighing 100 pounds?

Treatment for Ongoing Sinus Infection in 100 lb Adult

For an adult weighing 100 pounds with ongoing acute bacterial sinusitis, start with amoxicillin 1.5-4 grams daily for 10-14 days, and if there is no improvement after 72 hours, switch to high-dose amoxicillin-clavulanate (4 grams amoxicillin/250 mg clavulanate daily) or a respiratory fluoroquinolone. 1, 2

Initial Antibiotic Selection

For mild disease without recent antibiotic use (past 4-6 weeks):

• Amoxicillin 1.5-4 g/day is the first-line choice for 10-14 days 1, 2
• Alternative first-line options include cefpodoxime proxetil, cefuroxime axetil, or cefdinir 1
• For penicillin allergy, consider doxycycline, azithromycin, clarithromycin, or TMP-SMX, though these have 20-25% bacteriologic failure rates 1

For moderate disease OR recent antibiotic use (within 4-6 weeks):

• High-dose amoxicillin-clavulanate (4 g amoxicillin/250 mg clavulanate daily) is preferred 1
• Respiratory fluoroquinolones (levofloxacin 500-750 mg daily, moxifloxacin, or gatifloxacin) are equally effective alternatives 1
• Ceftriaxone 1 gram IM/IV daily for 5 days is another option 1

Dosing Considerations for 100 lb Patient

For a 100 lb (45 kg) adult, standard adult dosing applies 3:

• Amoxicillin: 500 mg three times daily OR 875 mg twice daily (totaling 1.5-2.6 g/day)
• High-dose amoxicillin-clavulanate: 875 mg/125 mg twice daily PLUS amoxicillin 875 mg twice daily (totaling 4 g amoxicillin/day) 4
• Levofloxacin: 500 mg once daily for 10-14 days OR 750 mg once daily for 5 days 5
• Doxycycline: 100 mg twice daily 3

Reassessment at 72 Hours

If no improvement after 3 days of initial therapy:

• Switch to broader-spectrum coverage based on initial agent limitations 1, 6
• If started on amoxicillin, escalate to high-dose amoxicillin-clavulanate or respiratory fluoroquinolone 1, 2
• Consider combination therapy: high-dose amoxicillin or clindamycin PLUS cefixime, or high-dose amoxicillin or clindamycin PLUS rifampin 1
• Important caveat: Rifampin should never be used as monotherapy and only for 10-14 days maximum due to rapid resistance development 1

Adjunctive Therapy

Intranasal corticosteroids are recommended as complementary treatment to reduce inflammation and improve drainage 2, 6

Supportive measures include:

• Adequate hydration 2
• Analgesics for pain relief 2
• Warm facial compresses 2
• Steam inhalation 2
• Sleeping with head elevated 2

Treatment Duration

• Continue antibiotics for 10-14 days total 1, 2
• Alternative approach: treat until symptom-free for 7 days 6
• Shorter 5-day courses with high-dose levofloxacin (750 mg daily) are FDA-approved and equally effective 5

When to Escalate Care

Refer to specialist or obtain imaging if:

• No response to appropriate antibiotic therapy after 72 hours despite medication change 1
• Recurrent sinusitis (≥3 episodes per year) 2, 6
• Suspected complications: meningeal signs, orbital symptoms (exophthalmos, periorbital edema, ocular mobility disorders), or severe unrelenting pain 1
• CT scan, fiberoptic endoscopy, or sinus aspiration for culture may be necessary 1

Common Pitfalls

Avoid fluoroquinolone overuse in mild disease, as widespread use promotes resistance in gut organisms 1

Recent research shows no benefit from doubling amoxicillin dose in standard amoxicillin-clavulanate formulations (high-dose vs standard-dose showed no difference in outcomes) 4, though guideline recommendations still support high-dose regimens for resistant organisms 1

Diarrhea is common with amoxicillin-clavulanate (40-43% of patients experience any diarrhea, 7-8% severe) 4