Will adding clarithromycin (a macrolide antibiotic) help a 2.9-year-old boy with persistent fever spikes on day 6 of illness, despite being on amoxicillin-clavulanate (Augmentin) for 5 days?

Should You Add Clarithromycin to Amoxicillin-Clavulanate for This Child?

No, adding clarithromycin to amoxicillin-clavulanate is not the appropriate next step for a 2.9-year-old with persistent fever on day 6 of illness despite 5 days of amoxicillin-clavulanate. Instead, you need to reassess for treatment failure, consider switching to high-dose amoxicillin alone (if not already using adequate dosing), or evaluate for complications requiring hospitalization.

Why Adding Clarithromycin Is Not Recommended

The fundamental problem is that amoxicillin-clavulanate is likely the wrong choice for this age group in the first place. For children under 3 years with community-acquired pneumonia, high-dose amoxicillin (90 mg/kg/day in 2 doses) is the first-line treatment for presumed Streptococcus pneumoniae, which is the most common bacterial pathogen at this age 1, 2. Amoxicillin-clavulanate is only indicated if the child is incompletely vaccinated against Haemophilus influenzae type b or has concurrent purulent otitis media 1.

Macrolides like clarithromycin are not appropriate for typical bacterial pneumonia in children under 3 years because atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae) are uncommon in this age group 1. The guidelines reserve macrolides for children ≥5 years old when atypical pneumonia is suspected 1, 2.

What You Should Do Instead

Immediate Reassessment (Critical Step)

Perform a thorough clinical reassessment to identify why the fever persists 1, 2. This includes:

• Review all culture results if any were obtained 1
• Meticulous physical examination looking for new findings 1
• Chest radiography to evaluate for complications like parapneumonic effusion, pneumatocele, or progression of infiltrates 1
• Assess for signs of severe disease requiring hospitalization: chest indrawing, central cyanosis, stridor, inability to tolerate oral intake 3
• Verify medication adherence and dosing - confirm the child actually received adequate doses 3

Treatment Algorithm Based on Reassessment

If the child is clinically stable without complications:

• Switch to high-dose amoxicillin monotherapy (90 mg/kg/day in 2 doses) if not already on adequate dosing 2, 4. Many treatment failures occur because providers underdose amoxicillin at 40-45 mg/kg/day instead of the recommended 90 mg/kg/day 2, 4.
• Continue for 5-7 days total and reassess within 48-72 hours 1, 2

If the child shows no improvement within 48-72 hours or deteriorates:

• Hospitalization is indicated for intravenous antibiotics 1, 2, 3
• Inpatient empiric therapy: Ampicillin or penicillin G IV (if fully immunized and local penicillin resistance is minimal), OR ceftriaxone/cefotaxime IV (if incompletely immunized or significant local resistance) 1, 2
• Add vancomycin or clindamycin if community-associated MRSA is suspected (severe pneumonia, necrotizing features, empyema) 1, 2

If parapneumonic effusion is identified:

• Obtain pleural fluid for Gram stain and culture 2
• Consider drainage depending on size and characteristics 1

Common Pitfalls to Avoid

Do not empirically add macrolides to beta-lactams in children under 3 years - this combination is only appropriate for children ≥5 years when you cannot distinguish bacterial from atypical pneumonia 1, 4. At 2.9 years old, pneumococcus dominates, and macrolide resistance in S. pneumoniae is common 5.

Do not continue failing therapy beyond 48-72 hours without reassessment 1, 2, 4. Persistent fever after 5 days of antibiotics demands investigation for complications, resistant organisms, or non-bacterial causes 1, 3.

Do not assume the clavulanate component adds necessary coverage - for typical pneumonia in this age group, it adds unnecessary side effects (particularly diarrhea) without improving outcomes unless specific indications exist 1, 6.

The Bottom Line

Your patient needs reassessment and likely a change in management strategy, not addition of clarithromycin. The persistent fever after 5 days suggests either inadequate initial antibiotic choice/dosing, a complication requiring drainage, resistant organisms, or a non-bacterial cause 1, 3. Adding clarithromycin to an already failing regimen will not address the underlying problem and delays appropriate intervention that could prevent morbidity.