Pseudomembranous colitis (antibiotic-associated diarrhoea)

Question 1

This colitis can be initiated by

Answer 1

the use of any antibiotic, esp.

• clindamycin
• lincomydn
• ampicillin
• cephalosporins (an exception is vancomycin)
• and even metronidazole.

Usually due to an overgrowth of the ‘superbug’ Clostridium difficile:

• which produces a toxin that causes specific inflammatory lesions,
• sometimes with a pseudomembrane
• and is becoming resistant to antibiotics.

It may occur, uncommonly, without antibiotic usage.

Question 2

Features

Answer 2

Profuse watery (possibly serous bloody) diarrhoea

Abdominal cramping and tenesmus, maybe fever

Within 2 d of taking antibiotic (can start up to 4–6 wks after usage)

Persists 2 wks (up to 6) after ceasing antibiotic

Watch for toxic megacolon.

Question 3

Diagnosed by

Answer 3

• characteristic lesions on sigmoidoscopy
• a tissue culture assay for C. difficile toxin.

Question 4

Treatment

Answer 4

Cease antibiotic

Choice 1: metronidazole 400 mg (o) tds for 7–10 d

or

Choice 2: vancomycin 125 mg (o) qid for 10 d