Colitis, Antibiotic-Associated

Key Features

Essentials of Diagnosis

• Most cases of antibiotic-associated diarrhea are not attributable to Clostridioides difficile and are usually mild and self-limited

• Symptoms of antibiotic-associated colitis vary from mild to fulminant almost all colitis is attributable to C difficile

• Diagnosis is established by stool assay in most cases

General Considerations

• Antibiotic-associated diarrhea is common

  • Characteristically occurs during antibiotic exposure, is dose-related, and resolves spontaneously after discontinuation

  • Most cases of diarrhea are mild and self-limited and do not require evaluation or treatment

• Antibiotic-associated colitis is almost always caused by C difficile

  • Colonizes the colon of 3% of healthy adults and 8% of hospitalized patients

  • Releases two toxins: TcdA and TcdB

  • C difficile is the major cause of diarrhea in patients hospitalized for > 3 days, affecting 15 of 1000 patients

  • C difficile–induced colitis most commonly develops after use of ampicillin, clindamycin, fluoroquinolones, and third-generation cephalosporins

  • Symptoms begin during or shortly after antibiotic therapy but may be delayed for up to 8 weeks

• A more virulent strain of C difficile (NAP1)

  • Contains an 18-base pair deletion of the TcdC inhibitory gene, resulting in higher toxin TcdA and TcdB production

  • Is more prevalent among hospital-associated infections (31%) than community-acquired infections (19%)

  • Has been associated with outbreaks of severe disease with up to 7% mortality

Demographics

• Antibiotic-associated colitis is found in

  • Hospitalized or recently hospitalized patients

  • Elderly or debilitated patients

  • Patients with inflammatory bowel disease

  • Persons who have received

• Multiple antibiotics or prolonged antibiotic therapy

• Proton pump inhibitor therapy

• Enteral tube feeding

• Chemotherapy

Clinical Findings

Symptoms and Signs

• Mild to moderate greenish, foul-smelling watery diarrhea with lower abdominal cramps in most patients

• Physical examination normal, or mild left lower quadrant tenderness

• Stools may have mucus but seldom gross blood

• Fulminant disease

  • Occurs in up to 10 % of patients

  • Characterized by fever; hemodynamic instability; and abdominal distention, pain, and tenderness

  • Most patients have profuse diarrhea (up to 30 stools/day)

  • However, diarrhea may be absent or appear to be improving in fulminant disease due to ileus

Differential Diagnosis

• Antibiotic-associated diarrhea (not related to C difficile)

• Other drug reaction

• Diarrhea due to enteral tube feedings

• Ischemic colitis

• Other bacterial diarrhea

• Inflammatory bowel disease

• Rarely, other organisms (staphylococci, Clostridium perfringens) are associated with pseudomembranous colitis

• Klebsiella oxytoca may cause a distinct form of antibiotic-associated hemorrhagic colitis

Diagnosis

Laboratory Tests

• Mild disease: no or minimal leukocytosis

• Severe disease

  • White blood count > 30,000/mcL

  • Serum albumin < 2.5 g/dL (due to protein-losing enteropathy)

  • Elevated serum lactate

  • Rising serum creatinine

• Rapid enzyme immunoassays (EIAs) detect the presence of C difficile toxins TcdA and TcdB ...