Introduction: infective colitis is an inflammatory condition of the large bowel caused by the presence of pathogenic organisms, and may be primary or secondary.

Incidence: the incidence varies widely depending on the causative organism. The most common type, pseudomembranous colitis, occurs in up to 1%of hospitalized patients, and is almost exclusively associated with antibiotic use.

Causative organisms

A number of different organisms have been implicated, and these include:

1. ▪ Clostridium difficile. This organism is responsible for pseudomembranous colitis. It is associated with the use of antibiotics, particularly the macrolides. Clinically a patient who may have been steadily improving suddenly deteriorates, with tachycardia and signs of hypovolaemia. There is profuse diarrhoea which is characteristically green in colour. Blood tests show a rising white count and inflammatory markers. If dehydration is severe then renal function may become compromised. The inflammatory process causes a fibrinous pseudomembrane to develop over the colonic mucosa. Treatment is with oral metronidazole or vancomycin. Parenteral antibiotics are not effective. If treatment is delayed toxic megacolon and/or perforation may occur. Mortality is reported to be as high as 30%.

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