Clostridioides difficile Colitis

Definition: antibiotic-associated colitis caused by toxin-producing Clostridioides difficile, a spore-forming anaerobic gram-positive bacillus. Disease is mediated by toxin A (enterotoxin) and toxin B (cytotoxin); the hypervirulent NAP1/BI/027 ribotype causes more severe disease.

Why the elderly: age above 65 is an independent risk factor. Contributory factors are recent antibiotics (clindamycin, cephalosporins, fluoroquinolones, co-amoxiclav), proton pump inhibitor use, hospitalisation or long-term care residence, tube feeding, comorbidity and reduced gut microbiota diversity. Pathy's notes a possible causal relationship between PPI therapy and C. difficile infection, and that frail and institutionalised older people have less diverse microbiota.

Clinical features: watery diarrhoea (three or more unformed stools in 24 hours), lower abdominal cramps, fever, and leucocytosis. In older adults it may present atypically as delirium, dehydration or unexplained leucocytosis. Essentials states that if a resident has severe fever, abdominal cramps or diarrhoea with or without blood or leucocytes in stool, initial evaluation for C. difficile should be performed.

Severe and fulminant disease: severe disease is defined by WBC above 15,000 cells/µl or serum creatinine at or above 1.5 mg/dl. Fulminant disease adds hypotension, shock, ileus or toxic megacolon. Paradoxical cessation of diarrhoea with abdominal distension signals ileus or toxic megacolon, not improvement.

Diagnosis: test only unformed stool from symptomatic patients. A two-step algorithm is standard — a sensitive screen (GDH antigen or NAAT/PCR) followed by a specific toxin EIA. NAAT positivity with toxin negativity may indicate colonisation rather than disease. Never perform a test of cure. Abdominal CT for suspected megacolon; flexible sigmoidoscopy shows pseudomembranes.

First principles of management: stop the inciting antibiotic wherever possible, stop the PPI if not clearly indicated, correct fluid and electrolyte losses, and avoid antimotility agents such as loperamide in acute severe disease.

Treatment of an initial episode: fidaxomicin 200 mg twice daily for 10 days is now first-line; oral vancomycin 125 mg four times daily for 10 days is an acceptable alternative. Metronidazole is no longer preferred and should be reserved for settings where neither is available.

Fulminant disease: oral vancomycin 500 mg four times daily (plus vancomycin per rectum if ileus) with intravenous metronidazole 500 mg 8-hourly. Early surgical review for subtotal colectomy or diverting loop ileostomy with colonic lavage.

Recurrence: occurs in 15–25% after a first episode and rises to 40–60% after subsequent episodes. First recurrence — fidaxomicin (standard or extended-pulsed) or tapered-pulsed vancomycin. Multiple recurrences — tapered-pulsed vancomycin, vancomycin followed by rifaximin, or faecal microbiota transplantation, reserved for those who have had appropriate antibiotic therapy for at least two recurrences.

Infection control: contact precautions with gowns and gloves; soap-and-water handwashing because alcohol rub does not kill spores; single room; sporicidal (chlorine-based) environmental cleaning; dedicated equipment; and antimicrobial stewardship as the single most effective preventive measure.

"The three cornerstones are stop the offending antibiotic, stop the PPI, and start targeted therapy."

"Severe disease is defined by a WBC above 15,000/µl or creatinine at or above 1.5 mg/dl."

"Alcohol hand rub does not kill spores — soap and water handwashing is mandatory."

"Cessation of diarrhoea with abdominal distension indicates ileus or toxic megacolon, not recovery."

"Fidaxomicin is preferred over vancomycin because of lower recurrence, with a number needed to treat of 10."