CSP Exam Prep Course: Clostridioides Difficile

Vocabulary practice flashcards covering pathophysiology, severity classification, diagnostic testing, treatment regimens, and clinical pearls for Clostridioides difficile infection (CDI) based on the NASP 2025 CSP Exam Prep Course.

Clostridioides difficile

A Gram-positive, spore-forming anaerobic bacillus that causes infection following antibiotic disruption of the gut microbiota, leading to overgrowth and toxin production.

Non-severe CDI

CDI disease severity defined by IDSA criteria as a white blood cell count of $< 15{,}000/̄̀u\text{L}$ ($< 15{,}000/\mu\text{L}$) and a serum creatinine ($\text{SCr}$) of $< 1.5\,\text{mg/dL}$.

Severe CDI

CDI disease severity defined by IDSA criteria as a white blood cell count of $\ge 15{,}000/\mu\text{L}$ or a serum creatinine ($\text{SCr}$) of $\ge 1.5\,\text{mg/dL}$.

Fulminant CDI

A critical presentation of CDI characterized clinically by hypotension, shock, ileus, or megacolon.

Initial CDI Episode (Preferred Regimen)

Fidaxomicin $200\,\text{mg}$ by mouth twice daily for $10\,\text{days}$.

Initial CDI Episode (Alternative Regimens)

Vancomycin $125\,\text{mg}$ by mouth $4$ times daily for $10\,\text{days}$, or metronidazole $500\,\text{mg}$ by mouth $3$ times daily for $10\text{--}14\,\text{days}$ (restricted to non-severe disease only).

First CDI Recurrence (Preferred Regimen)

Fidaxomicin $200\,\text{mg}$ by mouth twice daily for $10\,\text{days}$ OR twice daily for $5\,\text{days}$ followed by every other day for $20\,\text{days}$.

Fulminant CDI (Recommended Regimen)

Vancomycin $500\,\text{mg}$ by mouth or nasogastric tube $4$ times daily plus metronidazole $500\,\text{mg}$ intravenously every $8\,\text{hours}$, with consideration of rectal instillation of vancomycin if ileus is present.

Bezlotoxumab

An intravenous monoclonal antibody administered as a single $10\,\text{mg/kg}$ IV dose once during standard of care antibacterial therapy to reduce recurrence in high-risk patients; carries a precaution in patients with a history of CHF.

REBYOTA® (fecal microbiota, live-jslm)

An FDA-approved single rectal dose administered after antibiotic therapy to prevent recurrence in patients aged $\ge 18\,\text{years}$.

VOWST® (fecal microbiota spores, live-brpk)

An FDA-approved oral capsule regimen administered after antibiotic therapy to prevent recurrence in patients aged $\ge 18\,\text{years}$.

Two-Step CDI Diagnostic Algorithm

The preferred diagnostic testing method combining GDH (glutamate dehydrogenase) antigen detection with toxin EIA (enzyme immunoassay).

CDI Retesting Restriction

A clinical guideline rule requiring that only unformed stools are tested and that patients are not retested within $7\,\text{days}$ if symptoms persist.

CDI Management in Pregnancy

Oral vancomycin is the preferred agent due to minimal systemic absorption; fidaxomicin is considered if benefits outweigh risks, and metronidazole is generally avoided due to lower efficacy.

CDI Hand Hygiene Protocol

Hand hygiene protocol requiring washing hands with soap and water if hands are visibly soiled or during active infection, while alcohol-based hand rubs are acceptable for routine hand hygiene.

Probiotics in CDI

Therapeutic supplements that are not routinely recommended for either primary or secondary prevention of CDI according to clinical practice guidelines.

Fecal Microbiota Treatment (FMT) Timing

A treatment modality indicated for subsequent recurrences after a patient has experienced $3$ total CDI episodes.