Skip to content

Clostridium Difficile Infection (CDI)

Basics

  • Gram-positive, spore-forming anaerobic bacillus producing enterotoxin (toxin A) and cytotoxin (toxin B).
  • Transmission via fecal-oral route, spores survive months in environment.
  • Hypervirulent BI/NAP1/027 strain linked to increased morbidity and mortality.
  • Severity ranges from asymptomatic carrier to diarrhea, colitis, sepsis, perforation, death.

Epidemiology

  • Colonization rates: 2-10% community, 3-18% inpatients, 4-20% long-term care residents.
  • US healthcare-associated CDI incidence: 73/100,000; community-acquired: 52/100,000.
  • CDI accounts for 12% of healthcare-associated infections.

Etiology & Pathophysiology

  • Spores resist stomach acid, colonize colon after microbiome disruption (often due to antibiotics).
  • Toxins cause neutrophil recruitment and epithelial damage.
  • Not invasive; disease mediated by toxin effects.

Risk Factors

  • Age >65, hospitalization, long-term care residence.
  • Comorbidities: IBD, immunosuppression, liver/renal disease.
  • Antibiotics (especially clindamycin, ampicillin, cephalosporins, fluoroquinolones).
  • Acid suppression therapy.
  • Recurrence risk increases with each episode.

Prevention

  • Antibiotic stewardship to minimize unnecessary antibiotic use.
  • Contact precautions: gloves, gowns; soap and water handwashing (alcohol sanitizers ineffective).
  • Environmental disinfection with spore-killing agents (hypochlorite).
  • Patient isolation if possible.

Commonly Associated Conditions

  • Pseudomembranous colitis, toxic megacolon, sepsis, colonic perforation.

Diagnosis

History

  • Diarrhea (>3 watery stools/day), abdominal cramps, recent antibiotics or hospitalization.
  • Fever, anorexia, nausea possible.
  • Recent PPI or H2 blocker use.

Physical Exam

  • Abdominal tenderness, distension, diminished bowel sounds.
  • Signs of systemic illness: fever, tachycardia, hypotension, dehydration.

Differential Diagnosis

  • Infectious colitis: Salmonella, Shigella, Campylobacter, EHEC.
  • IBD, ischemic bowel, drug-induced diarrhea, intestinal obstruction.

Tests

  • CBC, BMP, lactate to assess severity.
  • Stool tests:
  • GDH antigen assay (85-95% sensitivity).
  • Toxin A/B enzyme immunoassays (63-94% sensitivity).
  • Nucleic acid amplification tests (NAATs) for toxin genes.
  • Imaging (CT): colonic wall thickening, inflammation, complications.
  • Endoscopy (flexible sigmoidoscopy): pseudomembranes (pathognomonic but not always present).

Severity Classification (SHEA/IDSA)

  • Mild/moderate: WBC <15,000 and creatinine <1.5× baseline.
  • Severe: WBC ≥15,000 or creatinine >1.5× baseline.
  • Severe/complicated: hypotension, shock, ileus, megacolon, lactic acidosis.

Treatment

General Measures

  • Discontinue inciting antibiotics if possible.
  • Avoid antimotility agents.
  • Avoid unnecessary PPIs.

Medications

  • First episode:
  • Fidaxomicin 200 mg PO BID × 10 days (preferred)
  • Vancomycin 125 mg PO QID × 10 days
  • Metronidazole 500 mg PO TID × 10 days (second-line)
  • First recurrence:
  • Fidaxomicin 200 mg PO BID × 10 days or extended pulse regimen.
  • Vancomycin tapered/pulsed regimen.
  • Second recurrence:
  • Fidaxomicin or vancomycin tapered + rifaximin.
  • Fulminant infection:
  • Vancomycin 500 mg PO/NG/rectal + IV metronidazole 500 mg q8h.
  • Surgical and critical care consult urgently.

Alerts

  • Oral/rectal vancomycin only; IV vancomycin ineffective.
  • Monitor renal function closely.

Second Line

  • Metronidazole PO if intolerant or unavailable alternatives.
  • Fecal microbiota transplant (FMT) highly effective for recurrent CDI (80-90% cure rate).

Adjunctive & Alternative

  • IVIG (limited evidence).
  • Probiotics (Lactobacillus acidophilus, Saccharomyces boulardii) for prevention alongside antibiotics.
  • Investigational: newer antibiotics, monoclonal antibodies, vaccines.

Admission and Nursing

  • Admit for severe dehydration, hemodynamic instability, inability to tolerate oral intake, or fulminant colitis.
  • IV fluids, electrolyte correction, monitor closely.

Ongoing Care

  • Avoid repeat stool testing post-treatment due to persistent shedding.
  • Monitor for relapse (15-30%), typically 2-10 days after treatment cessation.

Diet

  • Regular diet unless severe colitis requiring NPO status pending surgery.

Patient Education

  • Hand hygiene importance (soap and water).
  • Avoid unnecessary antibiotics.
  • Educate on transmission prevention.

Prognosis

  • Most improve with treatment.
  • 1-3% develop fulminant colitis requiring surgery.

Complications

  • Toxic megacolon, colonic perforation, sepsis, death.

Clinical Pearls:

  • Alcohol-based hand sanitizers do not kill C. difficile spores; wash hands with soap and water.
  • Do not test asymptomatic patients.
  • Vancomycin and fidaxomicin are first-line treatments.
  • Metronidazole reserved when first-line agents are contraindicated or unavailable.
  • FMT is effective for recurrent infection.