Pseudomembranous colitis

Disease Description (Causes and Symptoms)

• Summary of definition: Pseudomembranous colitis is a disease in which the normal intestinal flora is disrupted, mainly after antibiotic use, allowing Clostridioides difficile (formerly Clostridium difficile) to proliferate and produce toxins, causing inflammation and formation of a pseudomembrane on the colonic mucosa.
• Main causes and risk factors: Use of broad-spectrum antibiotics (especially clindamycin, third-generation cephalosporins, and fluoroquinolones), older age (especially ≥60 years), hospitalization or healthcare-facility exposure, chronic or severe illness, impaired kidney function, malnutrition, obesity, immunosuppression, and use of PPIs (proton pump inhibitors), among others.
• Brief pathophysiology: Suppression of normal intestinal bacteria allows C. difficile to proliferate → toxins A and B (especially toxin B) damage intestinal mucosal epithelial cells → inflammation, fibrin, mucus, and neutrophils accumulate to form a pseudomembrane → diarrhea, bleeding, and severe systemic symptoms occur.
• Main symptoms: Sudden diarrhea (usually watery, with a foul odor resembling rice-rinsing water), fever, abdominal pain (cramping), abdominal distension, nausea and vomiting, and rarely bloody stool. Blood tests may show an elevated white blood cell count; in severe cases, shock, hypotension, intestinal perforation, and sepsis may occur.

Treatment (Including Latest Recommendations, Precautions, Complications, and Self-Care)

• General principles
  • Stop the causative antibiotic (immediately if possible). Provide fluids, electrolyte replacement, and supportive care.
  • Infection control: Contact precautions (personal protective equipment); wash hands with soap and water (alcohol-based hand sanitizer is ineffective for removing spores); disinfect the environment (sodium hypochlorite-based disinfectants are recommended).
• Drug treatment (initial/nonsevere/severe)
  • Initial nonsevere or severe (non-fulminant) first-line treatment: Oral vancomycin 125 mg 4 times/day for 10 days OR fidaxomicin 200 mg 2 times/day for 10 days. (Recent guidelines recognize fidaxomicin as a recommended first-line option because it lowers the risk of recurrence.)
  • Metronidazole: No longer recommended as first-line treatment for mild to moderate disease (used exceptionally when no alternatives are available).
  • Fulminant disease (shock, ileus, severe hypotension, etc.): Oral (or rectal) vancomycin 500 mg 4 times/day plus intravenous metronidazole 500 mg every 8 hours. Surgical evaluation is necessary (for example, in cases of necrosis, perforation, or severe toxic megacolon).
• Recurrent CDI (Clostridioides difficile infection)
  • First recurrence: Fidaxomicin or a standard repeat course of oral vancomycin (or a vancomycin taper/pulse regimen).
  • Multiple recurrences (2 or more): Fecal microbiota transplantation (FMT) is recommended to restore the intestinal microbiota (according to the indications and protocols of each institution).
  • Patients at high risk of repeated recurrence (especially those with a high risk of recurrence): Consider combination treatment with bezlotoxumab (a single-dose intravenous infusion targeting toxin B).
• Surgical treatment
  • Emergency total colectomy (partial or complete colectomy) may be considered for toxic megacolon, intestinal perforation, or sepsis that does not respond to treatment.
• Complications and prognosis
  • Complications: Dehydration and electrolyte abnormalities, shock, intestinal perforation and peritonitis, toxic megacolon, sepsis, and death. Most patients improve with appropriate treatment, but the recurrence rate is approximately 15–25% after the first recurrence, and the risk increases with each subsequent recurrence.
• Self-care precautions
  • Replace fluids and electrolytes, and watch for dehydration caused by diarrhea.
  • Do not start or stop antibiotics on your own; consult your doctor if they have been prescribed.
  • Handwashing with soap and water, separating personal items, and disinfecting household surfaces (with bleach-based products) are recommended.

Checklist Before an Outpatient Visit (Including Items to Bring and Sample Questions)

• Items to prepare (submit or bring to the appointment)
  • A list of all medications currently being taken (including prescription drugs, OTC medicines, supplements, and probiotics), as well as records of antibiotic use within the past 3 months (drug name and duration).
  • Records of recent temperature, number of diarrhea episodes, stool characteristics (including amount and blood), and the date symptoms began.
  • Reports of recent test results, if available (blood tests, stool tests, abdominal imaging, etc.).
  • Any history of Clostridioides difficile infection (if applicable: treatment, timing, and whether it recurred).
• Points to tell the doctor in advance during the outpatient visit
  • Whether you recently underwent surgery or were hospitalized, and any underlying conditions (kidney disease, diabetes, immunosuppression, etc.).
  • Possibility of pregnancy or current pregnancy.
• Symptoms to record (useful during the appointment)
  • Number of diarrhea episodes per day, fever (temperature), severity and location of abdominal pain, urine output (if dehydration is suspected), and whether dizziness or fainting has occurred.

Examples of General Questions to Ask the Doctor

• "How likely is it that C. difficile is the cause of this diarrhea? What tests should I have?"
• "Can I continue taking my current medications, especially antibiotics and PPIs?"
• "What is the expected duration and what are the main side effects of the antibiotic or treatment you plan to prescribe?"
• "How likely is recurrence, and what can I do to reduce the risk of recurrence?"
• "How should I manage infection control, including isolation, disinfection at home, and when I can return to normal activities?"

Examples of Disease-Specific Questions

• "If this is a recurrence, would FMT (fecal microbiota transplantation) be appropriate in my situation? What does the procedure involve, and what are its risks?"
• "I am at high risk of recurrence (because of older age, multiple courses of antibiotics, etc.). Do you recommend or consider adjunctive treatment such as bezlotoxumab appropriate for me?"

(Note: Treatment choices should be decided with the treating doctor, taking into account the severity of the patient's symptoms, underlying conditions, medication access, insurance coverage, and other factors.)