What are the recommended antibiotics for pediatric community-acquired pneumonia (CAP) that do not cause watery stools?

Antibiotic Selection for Pediatric CAP Minimizing Diarrhea Risk

Amoxicillin at 90 mg/kg/day divided into 2 doses is the optimal first-line antibiotic for pediatric community-acquired pneumonia with the lowest risk of watery stools, as it causes significantly less diarrhea than amoxicillin-clavulanate or macrolides. 1

Outpatient Treatment Algorithm

Children Under 5 Years

• First-line: Amoxicillin 90 mg/kg/day in 2 divided doses (maximum 4 g/day) 1, 2
• This provides excellent coverage for Streptococcus pneumoniae, the most common bacterial pathogen 1
• Amoxicillin has minimal gastrointestinal side effects compared to alternatives 3, 4

Children 5 Years and Older

• First-line: Amoxicillin 90 mg/kg/day in 2 divided doses (maximum 4 g/day) 1, 2
• If atypical pathogens suspected (school-age children with gradual onset, no high fever): Add azithromycin 10 mg/kg on day 1, then 5 mg/kg/day on days 2-5 1, 2
• Note: Macrolides like azithromycin can cause diarrhea in 10-15% of patients, but this is typically less severe than with amoxicillin-clavulanate 5

Inpatient Treatment Algorithm

Fully Immunized Children (Low Risk)

• First-line: Ampicillin IV or Penicillin G IV 1, 2
• Alternative: Ceftriaxone 50-100 mg/kg/day IV every 12-24 hours 2
• These narrow-spectrum options have minimal impact on gut flora and low diarrhea rates 6

Not Fully Immunized or High-Risk Children

• First-line: Ceftriaxone or cefotaxime (150 mg/kg/day every 8 hours) 1, 2
• If MRSA suspected: Add clindamycin 10-13 mg/kg/dose IV every 6-8 hours (maximum 40 mg/kg/day) 1, 7, 2
• Clindamycin carries a risk of Clostridioides difficile infection and diarrhea in 2-20% of cases, but this risk is acceptable when MRSA coverage is necessary 7

Antibiotics to AVOID for Diarrhea Prevention

Amoxicillin-Clavulanate

• Causes diarrhea in 20-30% of pediatric patients due to clavulanate component 8
• Only use when β-lactamase-producing organisms (H. influenzae) are strongly suspected in unimmunized children 1, 2
• If used, ensure amoxicillin component is 90 mg/kg/day in 2 doses 1

Broad-Spectrum Cephalosporins (Outpatient)

• Cefuroxime and similar agents disrupt gut flora more than narrow-spectrum penicillins 6
• Reserve for treatment failures or documented resistance 6

Critical Pitfalls to Avoid

Common prescribing errors that increase diarrhea risk:

• Using amoxicillin-clavulanate as first-line when plain amoxicillin is appropriate 8, 5
• Prescribing macrolides as monotherapy for presumed bacterial (not atypical) pneumonia in children under 5 years 2, 5
• Underdosing amoxicillin at 40-45 mg/kg/day instead of the recommended 90 mg/kg/day, leading to treatment failure and need for broader agents 2

Treatment Duration and Monitoring

• Duration: 5-7 days for uncomplicated cases with clinical improvement 3, 4
• Reassessment: If no improvement within 48-72 hours, consider inadequate coverage or complications rather than immediately switching to broader agents 2, 9
• Local resistance patterns: Verify that local pneumococcal penicillin resistance is <10% to justify amoxicillin monotherapy 1, 9

Special Considerations for Penicillin Allergy

If true penicillin allergy exists and MRSA is not suspected:

• Mild allergy: Trial of cefpodoxime, cefprozil, or cefuroxime under supervision 1
• Severe allergy: Levofloxacin (for children who have reached growth maturity) or linezolid 1, 2
• Avoid clindamycin monotherapy unless local susceptibility data supports it and resistance is <10% 7