Snapshot An 89-year-old man with a past medical history of gastritis presents to the hospital for dehydration and watery diarrhea. He started having diarrhea and some weakness about 2 days ago and had not been able to keep up with his fluid intake. He has been taking omeprazole for over 30 years and was recently treated with clindamycin for a soft tissue infection. On laboratory evaluation, he has a marked leukocytosis. He is started on oral vancomycin. Introduction Classification Clostridioides difficile anaerobic, gram + rod produces 2 toxins that bind to intestinal mucosal cells forms heat and alcohol-resistant spores part of normal GI flora Epidemiology incidence common risk factors recent antibiotics use clindamycin ampicillin cephalosporins fluoroquinolones proton-pump inhibitors recent hospitalization advanced age Pathogenesis causes a pseudomembranous colitis and diarrhea characterized by yellow-white plaques in intestinal mucosa pseudomembranous plaques are made from fibrin toxin A is an enterotoxin that binds to the intestinal brush border toxin B is a cytotoxin and depolymerizes actin, disrupting the cytoskeleton Prognosis relapse occurs in ~20% of patients Presentation Symptoms crampy abdominal pain anorexia malaise diarrhea typically watery diarrhea occasionally may be bloody but without frank blood Physical exam fever dehydration abdominal tenderness to palpation rebound tenderness in severe cases Imaging Abdominal radiography indications if toxic megacolon is suspected for quick diagnosis and assess for early intervention findings dilated colon Abdominal computed tomography (CT) indication suspicion for pseudomembranous colitis findings marked thickening of the colonic wall (accordion sign) irregularity of bowel wall pericolonic stranding Studies Labs ↑ white blood cells ↓ hypoalbuminemia ↑ lactate diagnostic tests of the stool polymerase chain reaction for the organism detection of antigen + fecal leukocytes Making the diagnosis based on clinical presentation and stool studies Differential Ulcerative colitis distinguishing factors typically presents with bloody diarrhea can also present with dermatologic manifestations such as erythema nodosum Crohn disease distinguishing factors can be bloody or nonbloody can present with fistulas can also present with dermatologic manifestations such as erythema nodosum Treatment Management approach 10-day course of antibiotics Medical oral vancomycin indications resistant to metronidazole severe cases fidaxomicin indication recurrent cases oral metronidazole indications used as an alternative if vancomycin or fidaxomicin are not available used in addition to vancomycin if patients are refractory to monotherapy contraindicated in the elderly fecal microbiota transplant indication recurrent cases Complications Colonic perforation occurs in small percentage of patients Toxic megacolon occurs in small percentage of patients