Overview
Clostridium difficile (C. diff) infection is a bacterial illness that affects the colon, causing inflammation and diarrhea. It often develops after taking antibiotics, which disrupt the balance of good bacteria in the gut, allowing C. diff to grow out of control. The infection can range from mild to life-threatening.

Why It’s Important
C. diff is a major cause of healthcare-associated infections, especially in hospitals and nursing homes. If left untreated, it can lead to severe colon damage, dehydration, and even death. Recurrence is also common, making long-term management critical.

Quick Facts

• Most common in older adults and people taking or who recently took antibiotics

• Around 500,000 cases occur annually in the U.S., causing thousands of deaths

• Often spreads in healthcare settings, but can also occur in the community

• Chronic and acute forms exist depending on severity and recurrence

• Can be mild (watery stools) or severe (toxic megacolon)

What Happens in the Body
C. diff bacteria produce toxins (Toxin A and Toxin B) that damage the lining of the colon, leading to inflammation and cell death. The disruption of healthy gut flora, usually due to antibiotics, allows C. diff to thrive and release toxins that cause diarrhea and colitis.

Common Signs and Symptoms

• Watery diarrhea (3 or more times a day for 2+ days)

• Abdominal cramping or pain

• Fever

• Nausea

• Loss of appetite

• Dehydration

• In severe cases: blood or pus in stool, swollen belly, kidney failure, or toxic megacolon

Diagnosis

• Stool tests to detect C. diff toxins or DNA (PCR testing is common)

• Colonoscopy or sigmoidoscopy in severe or unclear cases

• Imaging (CT scan) if complications like toxic megacolon are suspected

• Seek medical attention if you have severe or persistent diarrhea—especially after antibiotic use

Treatment and Management
Treatment depends on the severity:

• Stop the offending antibiotic (if possible)

• Start targeted antibiotics: usually vancomycin or fidaxomicin

• In mild cases, metronidazole may be used

• Hydration support (oral or IV fluids)

• Fecal microbiota transplantation (FMT) for recurrent cases to restore healthy gut flora

• Strict infection control measures (hand washing, isolation in hospitals)

Risks and Complications

• Severe dehydration

• Toxic megacolon (life-threatening enlargement of the colon)

• Bowel perforation

• Kidney failure

• Recurrence: up to 25% of cases recur after initial treatment

Who Is at Risk

• People who have recently taken broad-spectrum antibiotics

• Hospitalized patients or those in long-term care facilities

• Individuals with weakened immune systems

• Older adults (especially over 65)

• People with a history of C. diff infection or inflammatory bowel disease

Related Conditions

• Antibiotic-associated diarrhea

• Pseudomembranous colitis

• Ulcerative colitis (sometimes confused with C. diff)

• Sepsis (if C. diff spreads systemically)

When to See a Doctor

• If you develop persistent diarrhea after taking antibiotics

• If diarrhea is accompanied by fever, blood in stool, or severe abdominal pain

• If symptoms don’t improve or worsen despite treatment

• If you’ve had C. diff before and symptoms return

Last Updated: June 19, 2025