Crohn's disease: emerging pathologic and bacterial spectrum.

The evolution, in recent years, of concepts of inflammatory bowel disease in part reflect improved methods of defining disease, especially with modern microbiologic methods, endoscopy and mucosal biopsy. Although clinicians have focused on idiopathic ulcerative colitis and Crohn's disease, a host of new entities are now becoming recognized. Many of these are bacterial, such as Yersinia- or Campylobacter-associated enterocolitis. Thus, a "new" group of inflammatory bowel diseases has recently emerged, some with newly described pathologic features and others reflecting improved methods of detection with newer microbiologic methods. With evolving methods of recognition, other entities will likely be described as causes of inflammatory bowel disease.