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Essentials of Diagnosis
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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
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General Considerations
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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
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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
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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
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Differential Diagnosis
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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
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