Pseudomembranous colitis is inflammation of the large intestine that produces raised yellowish-white patches, called pseudomembranes, on the inner lining of the colon. It is almost always caused by toxins made by the bacterium Clostridioides difficile (formerly called Clostridium difficile), usually after antibiotics have disrupted the normal gut bacteria that keep C. difficile in check. Treatment centers on stopping the offending antibiotic when possible and using specific antibiotics or other therapies that target the infection.
What Is Pseudomembranous Colitis? Causes And Treatment
The name describes what a doctor sees through a colonoscope, not a separate disease. Pseudomembranes are patches of dead cells, mucus, and inflammatory debris that sit on top of inflamed colon tissue. They are the visible signature of severe C. difficile infection.
Not everyone with a C. difficile infection develops these patches. Many people have the infection with diarrhea and colon inflammation but no pseudomembranes. The term pseudomembranous colitis is generally reserved for cases where these patches are present, which tends to mean more significant disease.
The two toxins that C. difficile produces, toxin A and toxin B, are what damage the colon lining. They break down the tight junctions between cells that line the colon, trigger intense inflammation, and cause the cell death that forms the pseudomembranes. This is well established. The toxins, not the bacterium itself invading tissue, drive most of the damage.
What Causes C. difficile Infection?
Antibiotic use is the dominant risk factor. When antibiotics kill off beneficial gut bacteria, C. difficile — which is often already present in small numbers — can multiply without competition and start producing toxins.
Almost any antibiotic can set this up, but some are more strongly linked than others. Clindamycin, fluoroquinolones, and broad-spectrum penicillins and cephalosporins are frequently implicated. The risk rises with longer courses, higher doses, and use of multiple antibiotics at once.
Other factors matter too:
- Age over 65 — the immune system becomes less efficient at controlling the bacterium
- Recent hospitalization or long-term care facility residence — these settings concentrate the bacterium and antibiotic use
- Previous C. difficile infection — recurrence is common
- Weakened immune system from illness or immunosuppressive medications
- Stomach acid-suppressing drugs — the evidence here is mixed but some studies suggest an association
- Inflammatory bowel disease — may increase susceptibility
Outside of healthcare settings, community-acquired C. difficile infection has become more recognized, sometimes in people without recent antibiotic exposure or healthcare contact. The reasons are not fully understood. Some cases may involve transmission from contaminated surfaces or food, but this is not firmly established.
What Are the Symptoms of Pseudomembranous Colitis?
Watery diarrhea is the hallmark. It typically develops during or shortly after a course of antibiotics, though it can appear up to several weeks after antibiotics are stopped. The diarrhea may be mild or severe, and in serious cases it can occur many times per day.
Other common symptoms include:
- Abdominal pain and cramping
- Fever
- Loss of appetite
- Nausea
- Dehydration
Severe cases can bring on a distended abdomen, rapid heart rate, low blood pressure, and signs of systemic illness. In the most serious form, called fulminant colitis, the colon can become dangerously dilated — a condition called toxic megacolon — or perforate. These are medical emergencies.
One detail worth knowing: bloody diarrhea is less common in C. difficile infection than in some other causes of colitis. When blood is present, doctors consider other diagnoses too.
How Is It Diagnosed?
Diagnosis starts with a stool test. The most common approach is a test that detects the toxins themselves or the genes that produce them. Many labs use a two-step process — a sensitive screening test followed by a more specific confirmatory test. This reduces false positives.
Colonoscopy with visualization of pseudomembranes can confirm the diagnosis, but it is not always necessary. It is more likely to be used when the stool tests are negative but clinical suspicion remains high, or when other conditions need to be ruled out.
Imaging such as a CT scan can show thickening of the colon wall and help assess severity, but it cannot confirm the diagnosis on its own.
An important limitation: testing should generally be done only on unformed stool from people with diarrhea. Testing people without diarrhea can pick up harmless colonization and lead to unnecessary treatment.
How Is Pseudomembranous Colitis Treated?
Treatment depends on severity. For mild to moderate cases, the first step is often to stop the antibiotic that triggered the infection, if that is medically safe. Some mild cases resolve on their own after the offending antibiotic is withdrawn.
When antibiotic treatment for the C. difficile infection itself is needed, the main options are oral vancomycin and fidaxomicin. Both are supported by clinical evidence and are recommended in major guidelines. Metronidazole was used more in the past but is now generally reserved for situations where the preferred drugs are unavailable, because it appears somewhat less effective.
For severe or fulminant cases, treatment may include high-dose oral vancomycin, sometimes with intravenous metronidazole added. Hospitalization for monitoring, fluids, and sometimes surgery may be necessary.
Recurrent infection is a significant problem, affecting a meaningful proportion of people who recover from a first episode. For recurrent cases, treatment options include a tapered or pulsed vancomycin regimen, fidaxomicin, or fecal microbiota transplantation. Fecal microbiota transplantation — transferring stool from a healthy donor into the patient’s colon — has strong evidence for treating recurrent C. difficile infection when standard antibiotics have failed. It restores a more normal gut bacterial community that can keep C. difficile in check.
Antidiarrheal medications like loperamide are generally avoided in C. difficile infection because they can slow the clearance of toxins from the colon. This is a widely held clinical precaution, though formal trial evidence is limited.
How Can Pseudomembranous Colitis Be Prevented?
Antibiotic stewardship is the most effective prevention strategy. Using antibiotics only when necessary, choosing the narrowest effective drug, and using the shortest effective course all reduce risk. This is well supported.
Hand hygiene matters. C. difficile spores are resistant to alcohol-based hand sanitizers. Washing with soap and water is more effective at physically removing spores. In healthcare settings, contact precautions and thorough environmental cleaning with sporicidal agents are standard practice.
For people who have had recurrent C. difficile infection, some clinicians use preventive strategies such as a course of vancomycin after a subsequent antibiotic exposure, or newer approaches like monoclonal antibodies or microbiome-based therapies. These are evolving areas. The evidence for some of these approaches is still developing, and they are not universally recommended.
Probiotics are often marketed for prevention, but the evidence is mixed and guidelines do not uniformly recommend them. Some trials suggest possible benefit, while others show none. The quality of evidence is not strong enough to make a firm recommendation either way.
What Is the Outlook?
Most people with C. difficile infection recover with treatment. Mild cases may resolve without specific antibiotics once the triggering antibiotic is stopped. Severe cases carry more risk, particularly in older adults and those with other serious health conditions.
Recurrence is the main challenge. After a first episode, a notable proportion of people experience another. After multiple episodes, the risk of further recurrence climbs. This cycle can be frustrating and disruptive, but treatment options for recurrent disease have improved.
Mortality from C. difficile infection is a real concern, especially in frail or elderly patients. It is one of the most common healthcare-associated infections and contributes to significant illness and death. This is why prompt diagnosis and appropriate treatment matter.
Frequently Asked Questions
Is pseudomembranous colitis contagious?
C. difficile can spread from person to person, usually through contact with contaminated surfaces or hands. The infection itself is not passed directly like a cold, but the bacterium can be transmitted, especially in healthcare settings.
Can pseudomembranous colitis go away without treatment?
Mild cases sometimes resolve after the triggering antibiotic is stopped, but this should be decided by a doctor. Moderate to severe cases need specific treatment, and delaying it can lead to serious complications.
How long does pseudomembranous colitis last?
With appropriate treatment, diarrhea often improves within a few days, but full recovery can take longer. Recurrence is common, so symptoms that return after treatment should be evaluated promptly.
Can I take anti-diarrheal medication for C. difficile diarrhea?
Anti-diarrheal drugs like loperamide are generally avoided because they may trap toxins in the colon and worsen the illness. Check with a doctor before taking anything for diarrhea during a known or suspected C. difficile infection.
