Pseudomembranous colitis is an infection of the colon usually caused by Clostridium difficilebacteria, although it can also be caused by other bacteria. It is characterized by fever, abdominal pain, and offensive-smelling diarrhea, but can progress to toxic megacolon (a serious complication that can result in perforation of the colon or invasion of the bloodstream by virulent bacteria), and even death.
Antibiotics that are active against a wide range of bacteria alter the normal bacterial flora of the bowel. As the competition of certain bacteria is killed off by these antibiotics, it can grow more readily. One such type of bacterium is the aforementioned Clostridium difficile, which elaborates a toxin responsible for the diarrhea characteristic of pseudomembranous colitis.
Although Clindamycin (Cleocin) is the antibiotic most commonly associated with the condition, most any antibiotic can cause it. A significant proportion of cases are attributed to cephalosporin antibiotics such as cephalexin and cefazolin. But because of the frequent use of this type of antibiotic, cephalosporins are not particularly more likely to cause pseudomembranous colitis than some other types of antibiotics.
Half of the cases of pseudomembranous colitis are not associated with risk factors. Diabetics, those recovering from recent major surgery, and the elderly, however, do seem to be more vulnerable. The use of ciproflocacin combined with a primary causative antibiotic such as clindamycin tends also to increase the mortality rate in those with the condition.
What often distinguishes those with pseudomembranous colitis from other antibiotic related diarrheal states is that the former tend to be lethargic and look sick. This may be due, in part, because blood tests often show that these patients have an elevated white blood cell count, low serum albumin, and anemia. Colonoscopies and sigmoidoscopies are still used to diagnose pseudomembranous colitis. But stool testing for some of the toxins produced by Clostridium difficile is now more commonly employed for initial diagnosis.
Treatment for pseudomembranous colitis usually includes discontinuation of the offending antibiotic, fluid replacement, other supportive care, and the introduction of either metronidazole (Flagyl) or vancomycin (Vancocin). Due to the expense of vancomycin and the risk of developing vancomycin-resistant organisms, the use of this antibiotic is often reserved for patients who relapse after metronidazole treatment.
Cholestyramine (Questran, Cholybar) may be used in combination with the primary treatment. This bile acid resin can be used to bind toxins produced by Clostridium difficile. Other treatments may include the use of the Saccharomyces boulardii yeast, kefir, or fecal bacteriotherapy.
If the infection cannot be controlled, a colectomy, or removal of the colon, may be required.