Clinical Commander

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gi.c-difficile.core.v1

Clostridioides difficile Infection

gastroenterologyacuteadultacuteoutpatientinpatient
Start encounter →Print handoutPRODUCTION

Primary guideline: IDSA/SHEA 2021 Focused Update (Johnson 2021, PMID 34164674 verified via PubMed MCP 2026-05-26). Key 2021 paradigm shift: metronidazole NO LONGER first-line; fidaxomicin and oral vancomycin are co-first-line; metronidazole only when neither available. Bezlotoxumab (Wilcox 2017 MODIFY I/II, PMID 28121498) reduces recurrence ~10% absolute; conditional recommendation for high-recurrence-risk patients during antibiotic course. Fecal microbiota live products (Rebyota = fecal-microbiota-live-jslm; Vowst = fecal-microbiota-spores-live-brpk) FDA-approved for recurrence prevention after antibiotic course. Fulminant CDI = hypotension/shock/ileus/megacolon → high-dose oral vancomycin 500 mg QID + IV metronidazole 500 mg q8h ± rectal vancomycin retention enema if ileus + mandatory surgical consult. RxCUIs verified live via RxNav 2026-05-26: fidaxomicin=1111103, vancomycin=11124, bezlotoxumab=1855048, metronidazole=6922, fecal-microbiota-live=2626724.

Entry points (5)

  • symptom
    ≥3 unformed stools in 24h with recent antibiotic / healthcare exposure (IDSA/SHEA 2021)
    diarrhea_3_plus_unformed_stools_24h
  • lab_abnormality
    Positive stool C. difficile test (NAAT + toxin or toxin EIA per IDSA/SHEA 2021)
    positive_cdiff_test
  • history
    Recent antibiotic exposure within 8 weeks + new diarrhea (IDSA/SHEA 2021)
    antibiotic_within_8_weeks
  • symptom
    Pseudomembranes seen on endoscopy
    pseudomembranous_colitis_on_endoscopy
  • problem_list
    Recurrent CDI (≥1 prior episode within 8 weeks)
    recurrent_cdiff

Required inputs (13)

  • agerequired
    demographic • used at CONTEXT
    Age ≥65 is severe-risk criterion + recurrence risk; bezlotoxumab indication (IDSA/SHEA 2021)
  • temperaturerequired
    vital • used at CONTEXT
    Fever ≥38.5 is severe / fulminant criterion (IDSA/SHEA 2021)
  • sbprequired
    vital • used at CONTEXT
    Hypotension defines fulminant CDI (IDSA/SHEA 2021)
  • hrrequired
    vital • used at CONTEXT
    Tachycardia + shock screen for fulminant
  • wbcrequired
    lab • used at INITIAL_WORKUP
    WBC ≥15,000 defines severe CDI (IDSA/SHEA 2021)
  • creatininerequired
    lab • used at INITIAL_WORKUP
    Cr >1.5 mg/dL defines severe CDI (IDSA/SHEA 2021)
  • albumin
    lab • used at INITIAL_WORKUP
    Hypoalbuminemia tracks severity
  • lactate
    lab • used at RED_FLAGS
    Elevation suggests fulminant CDI / megacolon / sepsis (IDSA/SHEA 2021)
  • cdiff_stool_testrequired
    lab • used at INITIAL_WORKUP
    NAAT + toxin EIA two-step OR toxigenic culture is preferred diagnostic algorithm (IDSA/SHEA 2021)
  • prior_cdi_episodesrequired
    history • used at CONTEXT
    ≥1 prior CDI defines recurrent; informs fidaxomicin / bezlotoxumab / FMT decision (IDSA/SHEA 2021)
  • recent_antibiotic_exposurerequired
    history • used at CONTEXT
    Triggers + risk factor; opportunity to discontinue inciting agent (IDSA/SHEA 2021)
  • ibd_immunocompromise
    history • used at CONTEXT
    IBD/immunocompromise increases severity + recurrence risk (IDSA/SHEA 2021)
  • abdominal_ct_if_fulminant
    imaging • used at RED_FLAGS
    Toxic megacolon, perforation, ileus identification (IDSA/SHEA 2021)

12-phase flow (12)

  1. 1FRAME
    Frame: toxin-mediated colitis from C. difficile; severity-grade (non-severe / severe / fulminant) drives antibiotic + procedural decisions (IDSA/SHEA 2021)
    inputs: age
    advance: CDI plausible by clinical context
  2. 2ENTRY
    Recognize ≥3 unformed stools/24h + recent antibiotic / healthcare exposure; positive stool test; recurrent CDI presentation (IDSA/SHEA 2021)
    advance: one entry trigger present
  3. 3CONTEXT
    Vitals, recent antibiotic / PPI / chemotherapy exposure, prior CDI episodes (for recurrence framing), IBD / immunosuppression, healthcare-vs-community-acquired (IDSA/SHEA 2021)
    inputs: age, temperature, sbp, hr, prior_cdi_episodes, recent_antibiotic_exposure, ibd_immunocompromise
    advance: context captured
  4. 4RED_FLAGS
    Fulminant CDI = hypotension/shock + ileus + megacolon → ICU + surgical consult; toxic megacolon (colon diameter >6 cm); perforation (IDSA/SHEA 2021)
    inputs: sbp, lactate, abdominal_ct_if_fulminant
    actions: workup.fulminant_cdiff
    advance: fulminant features identified or excluded
  5. 5INITIAL_WORKUP
    CBC, BMP, albumin, lactate; stool C. difficile (NAAT + toxin EIA two-step OR toxigenic culture); abdominal exam; KUB / CT if severe (IDSA/SHEA 2021)
    inputs: wbc, creatinine, cdiff_stool_test
    actions: panel.cbc, panel.renal
    advance: diagnosis confirmed + severity assessed
  6. 6BRANCHING_WORKUP
    CT abdomen if severe/fulminant — toxic megacolon, perforation, ileus; flexible sigmoidoscopy if needed and no megacolon; rule out alternate diarrhea etiologies (norovirus, IBD flare) (IDSA/SHEA 2021)
    inputs: abdominal_ct_if_fulminant
    actions: workup.toxic_megacolon
    advance: complications identified
  7. 7DIFFERENTIAL
    Differentiate from antibiotic-associated diarrhea without C. diff, viral gastroenteritis, IBD flare, microscopic colitis, ischemic colitis (IDSA/SHEA 2021)
    advance: C. diff confirmed
  8. 8RISK_STRATIFICATION
    Severity tier: non-severe (WBC <15k, Cr <1.5), severe (WBC ≥15k OR Cr ≥1.5), fulminant (hypotension/shock, ileus, megacolon); recurrence risk (age ≥65, prior CDI, immunocompromise) (IDSA/SHEA 2021)
    inputs: wbc, creatinine
    advance: severity + recurrence risk documented
  9. 9TREATMENT
    STOP inciting antibiotic if possible; severity-driven antibiotic (fidaxomicin or oral vancomycin first-line; metronidazole only if neither available); bezlotoxumab for recurrence-risk; FMT or fecal microbiota live (Rebyota) for recurrent CDI; surgery for fulminant refractory (IDSA/SHEA 2021)
    inputs: creatinine, wbc
    advance: treatment plan locked
  10. 10DISPOSITION
    Outpatient for non-severe; inpatient for severe; ICU + surgery for fulminant; contact precautions throughout (IDSA/SHEA 2021)
    inputs: sbp
    advance: destination set
  11. 11MONITORING
    Daily exam + stool frequency, daily CBC + Cr during treatment, lactate if fulminant; assess response by day 3-5 (IDSA/SHEA 2021)
    inputs: wbc, creatinine
    advance: response documented or escalated
  12. 12FOLLOWUP
    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
    advance: follow-up + prevention plan documented