Red Flags
- Fulminant CDI — hypotension/shock, ileus, megacolon — surgical consult; vancomycin PO 500 mg QID + IV metronidazole; consider colectomy[1]
- Severe CDI: WBC ≥15 ×10⁹/L OR creatinine ≥1.5× baseline — admit; oral fidaxomicin or vancomycin[1]
- Multiple recurrences (≥3 episodes) — faecal microbiota transplant or bezlotoxumab plus standard antibiotic; recurrence cycles can be life-altering[1]
- CDI in inflammatory bowel disease flare — high mortality; treat both; do NOT use anti-motility agents (loperamide)[1]
First-line treatment
Interventions
- Faecal microbiota transplant (FMT)[1]For ≥3 recurrent episodes despite appropriate antibiotic therapy; via colonoscopy, NG tube, or oral capsules. ~85% efficacy
- Discontinue inciting antibiotic where possible[1]Stop the offending antimicrobial (especially fluoroquinolones, clindamycin, broad-spectrum cephalosporins, carbapenems) where clinically feasible
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Fidaxomicin[1] | Macrocyclic antibiotic (preferred) | 200 mg PO BD × 10 days OR extended-pulsed regimen (200 mg BD × 5 days then alternate days × 20 days) | Per package weight-based dosing for ≥6 months | Preferred over vancomycin for initial episode and first recurrence per 2021 update; lower recurrence rate |
| Vancomycin (oral)[1] | Glycopeptide (oral, non-absorbed) | 125 mg PO QID × 10 days for non-fulminant; 500 mg PO QID for fulminant (with rectal vancomycin if ileus) | 10 mg/kg PO QID (max 125 mg) | Alternative first-line; first choice for fulminant disease and where fidaxomicin unavailable |
| Metronidazole (IV) for fulminant[1] | Nitroimidazole (parenteral adjunct) | 500 mg IV q8h plus oral/rectal vancomycin | — | ADJUNCT in fulminant CDI; oral metronidazole NO LONGER recommended for non-severe CDI per 2021 update |
| Bezlotoxumab[1] | Monoclonal antibody against C. difficile toxin B | 10 mg/kg IV single dose during standard antibiotic course | — | Reduces recurrence in high-risk patients (age ≥65, immunocompromised, severe CDI, prior recurrence). Avoid in NYHA III–IV CHF |
Fidaxomicin[1]
Macrocyclic antibiotic (preferred)
- Adult
- 200 mg PO BD × 10 days OR extended-pulsed regimen (200 mg BD × 5 days then alternate days × 20 days)
- Paediatric
- Per package weight-based dosing for ≥6 months
Preferred over vancomycin for initial episode and first recurrence per 2021 update; lower recurrence rate
Vancomycin (oral)[1]
Glycopeptide (oral, non-absorbed)
- Adult
- 125 mg PO QID × 10 days for non-fulminant; 500 mg PO QID for fulminant (with rectal vancomycin if ileus)
- Paediatric
- 10 mg/kg PO QID (max 125 mg)
Alternative first-line; first choice for fulminant disease and where fidaxomicin unavailable
Metronidazole (IV) for fulminant[1]
Nitroimidazole (parenteral adjunct)
- Adult
- 500 mg IV q8h plus oral/rectal vancomycin
- Paediatric
- —
ADJUNCT in fulminant CDI; oral metronidazole NO LONGER recommended for non-severe CDI per 2021 update
Bezlotoxumab[1]
Monoclonal antibody against C. difficile toxin B
- Adult
- 10 mg/kg IV single dose during standard antibiotic course
- Paediatric
- —
Reduces recurrence in high-risk patients (age ≥65, immunocompromised, severe CDI, prior recurrence). Avoid in NYHA III–IV CHF
Safety-net
Referral criteria
Clinical summary
Diagnosis and management of CDI in adults — fidaxomicin or vancomycin first-line; bezlotoxumab and FMT for recurrence.