Clostridium difficile and its cytotoxin in feces of patients with antimicrobial agent-associated diarrhea and miscellaneous conditions.

Fecal specimens from 223 subjects were evaluated for the presence of Clostridium difficile by use of a selective medium developed in our laboratory and for the presence of C. difficile cytotoxin. C. difficile and cytotoxin were detected in 89 and 83%, respectively, of patients with antimicrobial agent-associated pseudomembranous colitis (PMC). In patients in whom PMC was not documented, C. difficile and cytotoxin were present in only 37 and 21%, respectively. C. difficile and cytotoxin were also recovered from the feces of 6 and 3, respectively, of 13 antimicrobial recipients who did not have diarrhea. Although C. difficile appears to be a major cause of PMC, it is not responsible for at least some two-thirds of cases of antimicrobial agent-associated diarrhea in which PMC is not documented. Neither the recovery of C. difficile nor the detection of its cytotoxin should be considered diagnostic for C. difficile-induced disease.     

Microscopic colitis: collagenous colitis and lymphocytic colitis

Microscopic colitis is currently classified as a chronic inflammatory bowel disorder and encompasses two entities: lymphocytic colitis and collagenous colitis. Patients with microscopic colitis present with a well-tolerated chronic watery diarrhea, sometimes with abdominal pain. Colonoscopy is normal. Diagnosis of microscopic colitis is established by histologic examination of colonic biopsies, showing a thickened subsurface collagen band higher than 10 microm in collagenous colitis, and an increased number of surface intra-epithelial lymphocytes higher than 20 lymphocytes per 100 epithelial cells in lymphocytic colitis. Causes of microscopic colitis are still unknown, although a drug-induced etiology is found in some cases. Patients are usually treated with budesonide but recurrences are frequent.     

Collagenous colitis

Collagenous colitis is a newly described entity that clinically manifests itself as watery diarrhea of long-standing duration. The main histopathologic characteristic is the presence of a collagen band immediately beneath the colonic surface epithelium. Ultrastructurally, the collagen is deposited beneath the basement membrane, which is intact. Pathogenetically, an aberrant function of the pericryptal fibroblastic sheath may be involved.     

Antimicrobial prophylaxis

This paper discusses when antimicrobial prophylaxis should be initiated and when it is not recommended as an effective treatment or means of prophylaxis. Various surgical procedures take complete advantage of the effectiveness of such prophylaxis against the emergence of infection and complications; however, the possibility of superinfection is always present and should not be overlooked by the attending physician.     

Indeterminate colitis

Indeterminate colitis (IC) originally referred to those 10-15% of cases of inflammatory bowel disease (IBD) in which there was difficulty distinguishing between ulcerative colitis (UC) and Crohn's disease (CD) in the colectomy specimen. However, IC is increasingly used when a definitive diagnosis of UC or CD cannot be made at colonoscopy, in colonic biopsies or at colectomy. The diagnostic difficulties may explain the variably reported prevalence of IC. Clinically, most patients with IC evolve to a definite diagnosis of UC or CD on follow up. The role of ancillary tests in the distinction of UC from CD is reviewed. The low sensitivity of serological markers limits their usefulness. Other tests include upper endoscopy and magnetic resonance imaging. The definition of IC may not be a purely histological one derived from resected specimens, but rather a clinicopathological one. This review offers some personal observations and viewpoints, and proposes an approach to some of the relatively more esoteric combinations of findings.     

Antimicrobial polypeptides

The respiratory tract presents a large and potentially vulnerable surface to inhaled microbes. It is coated by a thin layer of secretions generated by airway epithelial cells, submucosal glands, resident and recruited phagocytes (neutrophils, eosinophils, monocytes, and macrophages) and alveolar epithelial cells, as well as substances that enter from blood plasma. More than 80 years ago, Alexander Fleming observed that respiratory secretions have microbicidal and microbistatic properties. He described the activity of lysozyme, one of the principal polypeptides of these secretions. Since then, a number of additional antimicrobial components have been identified, and there is increasing insight into their complex interactions. This review is an update of my previous summary of this area.