Clostridium difficile: when antibiotics push the gut over the edge

Clostridium difficile: When Antibiotics Cause the Gut to Overreact

Clostridium difficile, often shortened to C. difficile or simply C. diff, is a bacterium that lives in many people's intestines without causing problems. However, if the balance in the gut is disrupted, most often after a course of antibiotics, the bacterium can take over and trigger a severe inflammation of the large intestine called pseudomembranous colitis. In Denmark, it is the most common hospital-acquired gut infection, and the number of cases has steadily increased over the past twenty years.

The disease doesn't only affect elderly hospital patients. Younger, otherwise healthy patients can also contract it, and infection can occur outside of a hospital setting.

What are the symptoms?

Symptoms typically begin days to weeks after a course of antibiotics. The classic presentation includes:

• Watery, often foul-smelling diarrhoea, frequently 5-15 times a day
• Abdominal pain or cramps
• Low-grade fever
• Nausea and reduced appetite
• Fatigue and dehydration

In severe cases, high fever, blood in the stool, increasing abdominal pain, bloating, and in the worst cases, toxic megacolon can occur, where the large intestine dramatically expands and may rupture. Toxic megacolon requires urgent hospital admission and may necessitate surgical removal of the large intestine.

Why does it happen?

C. difficile produces two toxins (toxin A and toxin B) that attack the intestinal lining. The bacterium is only able to proliferate when the normal gut flora is weakened. This most often occurs after:

• Antibiotic treatment, particularly cephalosporins, clindamycin, ciprofloxacin, and broad-spectrum penicillins
• Hospitalisation, where exposure to spores from the environment is common
• Older age (over 65 years)
• Use of acid-suppressing medication (PPIs like omeprazole, pantoprazole)
• Weakened immune system
• Chronic inflammatory bowel disease

The bacterium forms spores that are extremely resistant. They survive cleaning with ordinary disinfectants and can remain for weeks on bed rails, door handles, or toilets. This is why alcohol-based hand sanitisers are ineffective against C. difficile. Only thorough hand washing with soap and water removes the spores.

How is it diagnosed?

Diagnosis requires three things:

1. Symptoms that fit the profile (especially watery diarrhoea after antibiotics)
2. Detection of C. difficile toxin in a stool sample, typically using a combination of GDH antigen and toxin PCR
3. Possibly sigmoidoscopy or colonoscopy in cases of doubt, where the white pseudomembranes on the mucous membrane that gave the disease its name can be observed

CT scans are used in severe cases to assess the appearance of the bowel and rule out megacolon.

Treatment

First-line treatment has changed in recent years. Today, the recommendations are:

• First: if possible, stop the offending antibiotic
• First episode: vancomycin tablets for 10 days or fidaxomicin for 10 days. Metronidazole is rarely used as a first-line treatment anymore due to its lower efficacy.
• First recurrence: fidaxomicin or vancomycin in a pulsed/tapered regimen
• Repeated recurrences (≥2): faecal microbiota transplantation (FMT). Donor stool is transferred to the patient, most often via colonoscopy, to normalise the gut flora. The success rate is around 85-90 percent for recurrences, making it one of the most effective treatments available in modern gastroenterology.

Probiotics may offer a mild protective effect during antibiotic courses but are not a treatment in themselves.

In cases of severe colitis, septic shock, or toxic megacolon, emergency surgery may be necessary.

When should you seek medical attention?

Contact your GP or an emergency department if:

• You have watery diarrhoea that lasts for more than a week, especially after a course of antibiotics
• You have blood in your stool
• You have a high fever accompanied by abdominal pain
• You are very tired, have difficulty drinking enough, or are losing weight rapidly

For elderly or frail individuals, do not wait. Early treatment prevents complications.

Frequently Asked Questions

Can I get C. diff without having taken antibiotics? Yes, but it is rare. Antibiotics are by far the most common trigger, but the elderly, immunocompromised individuals, and those on proton pump inhibitors can also contract it without prior antibiotic use.

Can it spread to my relatives? The bacterial spores can spread. Wash hands with soap and water (not alcohol gel), thoroughly clean bathrooms and toilets, and use separate towels as long as you have diarrhoea.

How long does the treatment last? The antibiotic course itself is ten days. Many feel better after two or three days, but diarrhoea can last up to a week or more. 15-25 percent experience a recurrence within two months.

What is faecal transplantation, and is it unpleasant? It involves transferring carefully screened stool from a healthy donor into your gut, most often during a colonoscopy. It might sound unusual, but it is one of the most effective treatments for repeated recurrences. Donors are rigorously screened for infections and diseases.

References

1. Johnson S, Lavergne V, Skinner AM, et al. Clinical Practice Guideline by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA): 2021 Focused Update Guidelines on Management of Clostridioides difficile Infection in Adults. Clin Infect Dis. 2021;73(5):e1029-e1044. PubMed
2. van Prehn J, Reigadas E, Vogelzang EH, et al. European Society of Clinical Microbiology and Infectious Diseases: 2021 update on the treatment guidance document for Clostridioides difficile infection in adults. Clin Microbiol Infect. 2021;27 Suppl 2:S1-S21. PubMed
3. Sundhed.dk. Clostridioides difficile-infektion (lægehåndbogen).
4. Khanna S, Pardi DS. Clinical implications of antibiotic-associated diarrhea and Clostridioides difficile infection. Aliment Pharmacol Ther. 2023;57(5):560-572. PubMed

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This article provides general information and does not replace a medical consultation. Please contact your GP if you experience symptoms.