Primary pathogen (Clostridioides difficile (toxin-producing strains) · toxin A and toxin B)
Clinical context (Antibiotic-associated diarrhea · healthcare- and community-associated · high asymptomatic colonization in infants)
First-line therapy
Vancomycin • p.o. • 10–10 mg/kg/dose • 4×/day
Max 125 mg/dose · Max 500 mg/day · Duration: 10 days · Oral or enteral route only — i.v. vancomycin does not treat CDI · extend to 14 days if improving but not resolved
Enter weight on Kids to calculate doses
Fidaxomicin • p.o. • 20–20 mg/kg/dose • 2×/day
Max 80 mg/dose · Duration: 10 days · FDA Table 1 · ≥6 months of age · oral suspension 40 mg/mL
• Fidaxomicin: second or subsequent recurrence (preferred per IDSA adult guidance and SUNSHINE pediatric trial); initial episode when available and cost/access allow — lower recurrence vs vancomycin at 30 days (FDA, AAP 2023, IDSA/SHEA).
• Metronidazole oral: alternative for nonsevere initial or first recurrent CDI when oral vancomycin unavailable — slower symptom resolution vs vancomycin in observational data; no longer first-line (IDSA/SHEA 2017, AAP 2023).
• Metronidazole i.v.: adjunct to oral/enteral vancomycin in severe or fulminant CDI; give with high-dose oral vancomycin (10 mg/kg/dose QID, max 500 mg/dose) — i.v. metronidazole alone is insufficient (IDSA/SHEA Table 4).
• Severe/fulminant CDI: high-dose oral vancomycin (max 500 mg/dose QID) ± i.v. metronidazole; rectal vancomycin if ileus or unable to tolerate enteral therapy — hospitalize (AAP, IDSA/SHEA).
• Recurrent CDI (≥2nd episode): fidaxomicin or vancomycin taper-and-pulse regimen; consider fecal microbiota transplantation in multiply recurrent disease per pediatric ID/GI — do not use bezlotoxumab routinely in children (AAP 2023, IDSA/SHEA).
Enter weight on Kids to calculate doses
Clinical notes
• Test only symptomatic children with unexplained new-onset diarrhea (≥3 unformed stools in 24 h) — do not test formed stool or screen asymptomatic patients (IDSA/SHEA, AAP 2023).
• Avoid C. difficile testing in infants <12 months; use caution in children <2 years — high colonization rates; evaluate alternative causes of diarrhea before testing (AAP 2023, ESPGHAN).
• Discontinue the inciting antibiotic whenever possible — may resolve symptoms without CDI-directed therapy and limits further dysbiosis (IDSA/SHEA, AAP).
• Recurrent CDI occurs in ~20–30% of children: first recurrence — oral vancomycin 10 days; second/subsequent — fidaxomicin or vancomycin taper/pulse; consider FMT for multiply recurrent disease per ID/GI (IDSA/SHEA, AAP SUNSHINE trial).
• Do not repeat stool testing within 4 weeks or as test-of-cure — PCR/toxin assays may remain positive after successful treatment (IDSA/SHEA, AAP).
• IDSA / SHEA — Clinical Practice Guidelines for Clostridioides difficile Infection (2017)
