Internal Medicine

P1: SBT

0521779407-03a CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:18

134 Antibiotic-Associated Colitis

tests

Basic Tests

■blood: CBC

■stool for culture, O&P to rule out other possibilities

Imaging

■plain films of the abdomen to rule out toxic megacolon

Specific Diagnostic Tests

■ELISA assay (stool)

➣rapid test to detect the presence of C. difficile toxin in stool

➣most commonly used and widely available

➣sensitivity: 70–90%; specificity: 99%

■Cytotoxicity assay (stool)

➣gold standard for the identification of C. difficile cytotoxins

➣sensitivity: 94–100%; specificity: 100%

➣expensive with turn-around time of 2–3 days

➣Sigmoidoscopy or colonoscopy

recommended when diagnosis in doubt and has to be estab-

lished quickly

look for pseudomembranes

differential diagnosis

n/a

management

What to Do First

■discontinue inciting antibiotic if possible

General Measures

■assess severity

specific therapy

Initial Therapy

■oral metronidazole 500 mg TID or 250 mg QID for 10–14 days is the

initial choice for treatment

■alternative first-line agent is oral vancomycin 125 mg QID

■both metronidazole and vancomycin equally effective but metron-

idazole is much less expensive; vancomycin can lead to selection of

vancomycin-resistant enterococci

■oral Bacitracin alternative but not readily available

■for severe infections: oral metronidazole first; if no response in

48 hr, switch to oral vancomycin; if still no improvement, escalate

the vancomycin dose at 48-hour intervals up to 500 mg QID