Clostridioides difficile (C. diff)
Antibiotic-associated colitis — recognition, isolation and management
Clostridioides difficile (C. diff) is a bacterium that can cause severe diarrhoea and inflammation of the colon. It most commonly occurs after antibiotic use and is a leading cause of healthcare-associated infections in hospitals and care homes. Understanding risk, symptoms, and the critical importance of hygiene and isolation helps prevent spread.
What is C. difficile?
Clostridioides difficile (formerly Clostridium difficile) is a spore-forming bacterium that produces toxins damaging the lining of the large bowel. In healthy people, the normal gut bacteria (microbiome) keep C. diff under control. However, when antibiotics disrupt this balance — killing off many normal bacteria — C. diff can multiply rapidly and produce its toxins, causing C. difficile infection (CDI). CDI ranges from mild diarrhoea to severe, life-threatening colitis (inflammation of the colon) with a risk of toxic megacolon — a dangerous, potentially fatal complication. C. diff produces spores that are extremely resistant to most disinfectants, including alcohol-based hand gels, making thorough hand washing with soap and water and environmental decontamination essential infection control measures.
Risk Factors & Causes
The most important risk factor for CDI is recent antibiotic use — particularly broad-spectrum antibiotics such as clindamycin, cephalosporins, fluoroquinolones (e.g. ciprofloxacin), and broad-spectrum penicillins. Even a short course of antibiotics can disrupt the microbiome sufficiently to allow C. diff to flourish. Other significant risk factors include age over 65, hospitalisation or residence in a care home, proton pump inhibitor (PPI) use, immunosuppression, abdominal surgery, and previous CDI (which substantially increases the risk of recurrence). C. diff spores can survive in the environment for months on surfaces, equipment, and clothing, making healthcare settings a particular risk environment.
Signs & Diagnosis
The hallmark of CDI is diarrhoea — typically watery, frequent (three or more loose stools per day), and often with a distinctive offensive odour. Abdominal cramps and tenderness, fever, nausea, and loss of appetite are common. Severe CDI is indicated by features such as a very high white blood cell count, rising creatinine (suggesting dehydration or kidney involvement), high fever, severe abdominal pain, or ileus (gut paralysis). Diagnosis is by stool testing using a two-stage approach: GDH antigen detection followed by toxin A/B enzyme immunoassay, with PCR if required — as recommended by PHE. Clinical evaluation should also assess severity using established criteria to guide the intensity and urgency of treatment, as severe CDI requires hospital admission and specialist input.
Prevention & Infection Control
Preventing the spread of C. diff requires strict infection control measures. Patients with CDI must be isolated in a single room with dedicated toilet facilities. Staff and visitors must use gloves and aprons when entering the room. Crucially, alcohol-based hand gel does NOT kill C. diff spores — hand washing with soap and water is essential after any contact with an infected patient or their environment. Surfaces must be cleaned with a chlorine-based disinfectant. Antibiotic stewardship — prescribing antibiotics only when truly necessary, for the shortest effective duration, and using the narrowest-spectrum agent appropriate — is the most effective long-term strategy for reducing CDI rates. In hospitals, CDI is a mandatory notifiable condition reported to Public Health England. If you have had CDI, always inform any healthcare professional treating you in the future, as your risk of recurrence remains elevated for several years.