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gi.c-difficile.core.v1PRODUCTION
gi.c-difficile.core.v1

Clostridioides difficile Infection

gastroenterologyacuteadult
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Encounter flow

12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Frame: toxin-mediated colitis from C. difficile; severity-grade (non-severe / severe / fulminant) drives antibiotic + procedural decisions (IDSA/SHEA 2021)

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CDI plausible by clinical context

Patient inputs (13)

Age ≥65 is severe-risk criterion + recurrence risk; bezlotoxumab indication (IDSA/SHEA 2021)

Fever ≥38.5 is severe / fulminant criterion (IDSA/SHEA 2021)

Hypotension defines fulminant CDI (IDSA/SHEA 2021)

Tachycardia + shock screen for fulminant

≥1 prior CDI defines recurrent; informs fidaxomicin / bezlotoxumab / FMT decision (IDSA/SHEA 2021)

Triggers + risk factor; opportunity to discontinue inciting agent (IDSA/SHEA 2021)

WBC ≥15,000 defines severe CDI (IDSA/SHEA 2021)

Cr >1.5 mg/dL defines severe CDI (IDSA/SHEA 2021)

NAAT + toxin EIA two-step OR toxigenic culture is preferred diagnostic algorithm (IDSA/SHEA 2021)

IBD/immunocompromise increases severity + recurrence risk (IDSA/SHEA 2021)

Hypoalbuminemia tracks severity

Elevation suggests fulminant CDI / megacolon / sepsis (IDSA/SHEA 2021)

Toxic megacolon, perforation, ileus identification (IDSA/SHEA 2021)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (5)

5 need judgement
  • informationallife_threateningfulminant_cdi
    Hypotension / shock / ileus / megacolon (colon dilation >6 cm) on imaging (IDSA/SHEA 2021)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningtoxic_megacolon_complication
    Colonic dilation >6 cm + systemic toxicity (IDSA/SHEA 2021)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveresevere_cdi_per_idsa
    WBC ≥15,000 OR Cr ≥1.5 mg/dL (IDSA/SHEA 2021)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderaterecurrent_cdi_high_recurrence_risk
    ≥1 prior CDI episode + high recurrence risk factors (age ≥65, immunocompromise, severe disease, prior recurrence) (IDSA/SHEA 2021)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatefailure_to_respond_day_5
    No clinical improvement by day 5 of appropriate antibiotic therapy (IDSA/SHEA 2021)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

This dossier does not reference any calculators.

Recommended regimen

C. difficile infection — severity-driven antibiotic + recurrence prevention (IDSA/SHEA 2021 focused update)
axis: cdiff_severity_pathwaystep 1 - Step 1 — Initial / non-severe CDI (first episode)
Selected step "Step 1 — Initial / non-severe CDI (first episode)" — WBC <15,000 AND Cr <1.5 mg/dL AND no fulminant features
  • fidaxomicin
    first line
    macrocyclic_antibiotic
    200 mg PO BID x 10 days • PO • BID
    triggers: initial_episode, non_severe
    IDSA/SHEA 2021 — fidaxomicin preferred (lower recurrence vs vancomycin; Louie 2011 NEJM PMID 21288078 non-inferior cure with lower 25-week recurrence)
    rxcui 1111103
  • vancomycin
    first line
    glycopeptide_oral
    125 mg PO QID x 10 days • PO • QID
    triggers: initial_episode, non_severe, fidaxomicin_unavailable_or_cost
    IDSA/SHEA 2021 — oral vancomycin equally acceptable first-line; lower cost
    rxcui 11124
  • metronidazole
    second line
    nitroimidazole
    500 mg PO TID x 10 days • PO • TID
    triggers: fidaxomicin_AND_vancomycin_unavailable, mild_non_severe_only
    IDSA/SHEA 2021 — metronidazole NO LONGER preferred and only when fidaxomicin and vancomycin unavailable
    rxcui 6922

outpatient playbook — drug actions (4)

  1. 1. fidaxomicin
    rxcui 1111103
    200 mg PO BID x 10 days • PO • BID
    trigger: Non-severe or severe first episode (IDSA/SHEA 2021)
    Lower recurrence vs vancomycin
  2. 2. vancomycin (alternative)
    rxcui 11124
    125 mg PO QID x 10 days • PO • QID
    trigger: First-line alternative; fidaxomicin unavailable / cost
    IDSA/SHEA 2021 — equally acceptable first-line
  3. 3. discontinue inciting antibiotic
    Stop or substitute non-CDI-promoting agent if possible • PO/IV • one-time
    trigger: CDI diagnosis (IDSA/SHEA 2021)
    Cornerstone of management
  4. 4. oral hydration + electrolyte replacement
    Oral rehydration solution • PO • continuous
    trigger: Diarrhea-related volume loss
    Supportive care

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: ≥3 unformed stools in 24h with recent antibiotic / healthcare exposure (IDSA/SHEA 2021); Positive stool C. difficile test (NAAT + toxin or toxin EIA per IDSA/SHEA 2021); Recent antibiotic exposure within 8 weeks + new diarrhea (IDSA/SHEA 2021).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Clostridioides difficile Infection** (gi.c-difficile.core.v1).
Phenotype framing: Differentiate from antibiotic-associated diarrhea without C. diff, viral gastroenteritis, IBD flare, microscopic colitis, ischemic colitis (IDSA/SHEA 2021)
Scope: Frame: toxin-mediated colitis from C. difficile; severity-grade (non-severe / severe / fulminant) drives antibiotic + procedural decisions (IDSA/SHEA 2021)

No severity triggers fired against current inputs.

Plan

Regimen axis: **C. difficile infection — severity-driven antibiotic + recurrence prevention (IDSA/SHEA 2021 focused update)** — step "Step 1 — Initial / non-severe CDI (first episode)".
1. fidaxomicin 200 mg PO BID x 10 days PO BID (macrocyclic_antibiotic, first line) — IDSA/SHEA 2021 — fidaxomicin preferred (lower recurrence vs vancomycin; Louie 2011 NEJM PMID 21288078 non-inferior cure with lower 25-week recurrence)
2. vancomycin 125 mg PO QID x 10 days PO QID (glycopeptide_oral, first line) — IDSA/SHEA 2021 — oral vancomycin equally acceptable first-line; lower cost
3. metronidazole 500 mg PO TID x 10 days PO TID (nitroimidazole, second line) — IDSA/SHEA 2021 — metronidazole NO LONGER preferred and only when fidaxomicin and vancomycin unavailable

Setting playbook (outpatient) — Diagnose non-severe CDI; initiate fidaxomicin or vancomycin 10-day course; stop inciting antibiotic; arrange follow-up; monitor for severity progression (IDSA/SHEA 2021)
4. fidaxomicin 200 mg PO BID x 10 days PO BID — Non-severe or severe first episode (IDSA/SHEA 2021) (Lower recurrence vs vancomycin)
5. vancomycin (alternative) 125 mg PO QID x 10 days PO QID — First-line alternative; fidaxomicin unavailable / cost (IDSA/SHEA 2021 — equally acceptable first-line)
6. discontinue inciting antibiotic Stop or substitute non-CDI-promoting agent if possible PO/IV one-time — CDI diagnosis (IDSA/SHEA 2021) (Cornerstone of management)
7. oral hydration + electrolyte replacement Oral rehydration solution PO continuous — Diarrhea-related volume loss (Supportive care)

Non-pharmacologic actions:
- Soap-and-water handwash (alcohol gel does not inactivate spores) (IDSA/SHEA 2021)
- Contact precautions if shared bathroom / caregiver exposure (IDSA/SHEA 2021)
- PPI deprescribing if no clear indication (IDSA/SHEA 2021)
- Avoid antimotility agents in severe CDI (IDSA/SHEA 2021)
- Recurrence surveillance for 8 weeks (IDSA/SHEA 2021)

AVOID / contraindication checks:
- Antimotility_agents_avoid_in_severe_or_fulminant_CDI (IDSA/SHEA 2021)
- Metronidazole_no_longer_first_line_only_if_fidaxomicin_AND_vancomycin_unavailable (IDSA/SHEA 2021)
- Bezlotoxumab_caution_CHF_volume_overload (Wilcox 2017 MODIFY)
- Fmt_screen_donor_for_pathogens_inc_MDR (IDSA/SHEA 2021)
- Vancomycin_oral_minimal_systemic_absorption_use_oral_form_not_IV

Monitoring

Regimen monitoring:
- stool frequency daily (IDSA/SHEA 2021)
- CBC q1 2 days during severe or fulminant (IDSA/SHEA 2021)
- Cr q1 2 days during severe or fulminant (IDSA/SHEA 2021)
- lactate q4 6h in fulminant (IDSA/SHEA 2021)
- response to therapy by day 3 to 5 (IDSA/SHEA 2021)
- test of cure NOT recommended in asymptomatic (IDSA/SHEA 2021)
- recurrence surveillance for 8 weeks post treatment (IDSA/SHEA 2021)

Setting (outpatient) monitoring:
- Symptoms day 3-5 — improvement expected (IDSA/SHEA 2021)
- Repeat WBC / Cr if worsening (IDSA/SHEA 2021)
- No test-of-cure in asymptomatic patients (IDSA/SHEA 2021)

Follow-up plan: Total 10-day fidaxomicin or vancomycin course; bezlotoxumab single infusion during antibiotic course (≥1 recurrence-risk feature) (IDSA/SHEA 2021); fecal microbiota live (Rebyota) or FMT for recurrent CDI; avoid re-exposure; PPI deprescribing if possible
- Close-out criterion: follow-up + prevention plan documented

Monitoring phase: Daily exam + stool frequency, daily CBC + Cr during treatment, lactate if fulminant; assess response by day 3-5 (IDSA/SHEA 2021)

Disposition

Current setting: outpatient — Diagnose non-severe CDI; initiate fidaxomicin or vancomycin 10-day course; stop inciting antibiotic; arrange follow-up; monitor for severity progression (IDSA/SHEA 2021)

Disposition criteria:
- Continue outpatient: clinically stable + improving (IDSA/SHEA 2021)
- Admit: severe CDI features OR clinical deterioration (IDSA/SHEA 2021)

Escalation triggers (move to higher acuity):
- WBC ≥15k or Cr ≥1.5 → severe CDI tier (consider admission) (IDSA/SHEA 2021)
- Hypotension / ileus / megacolon → ED + ICU (IDSA/SHEA 2021)
- Failure to improve by day 5 → re-evaluate diagnosis + severity (IDSA/SHEA 2021)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Hypotension / shock / ileus / megacolon (colon dilation >6 cm) on imaging (IDSA/SHEA 2021)
- [LIFE_THREATENING] Colonic dilation >6 cm + systemic toxicity (IDSA/SHEA 2021)
- [SEVERE] WBC ≥15,000 OR Cr ≥1.5 mg/dL (IDSA/SHEA 2021)

Citations

- IDSA/SHEA 2021 Focused Update: Clinical Practice Guideline on Management of C. difficile Infection in Adults [PMID:34164674](https://pubmed.ncbi.nlm.nih.gov/34164674/)
- Cited evidence (PMID 21288078) [PMID:21288078](https://pubmed.ncbi.nlm.nih.gov/21288078/)
- Cited evidence (PMID 28121498) [PMID:28121498](https://pubmed.ncbi.nlm.nih.gov/28121498/)

Last reconciled with current guidelines: 2026-05-26.
References
  • IDSA/SHEA 2021 Focused Update: Clinical Practice Guideline on Management of C. difficile Infection in Adults — PMID:34164674
  • Cited evidence (PMID 21288078) — PMID:21288078
  • Cited evidence (PMID 28121498) — PMID:28121498