Mycobacterial diseases of the gut: some impact from molecular biology.

Mycobacterial diseases of the gut: some impact from molecular biology At present Crohn's disease is by far the most important unresolved intestinal problem with a presumptive myco- bacterial association. When the progress of Crohn's disease research throughout the 20th century is reviewed from the vantage ofthe 21st, some familiar patterns will be recognised. From its earliest definitive descriptions,'2 Crohn's disease was suspected of having a mycobacterial cause, but with the failure of the available techniques of microscopy and culture to show specific pathogens, the likelihood of mycobacterial involvement was difficult to sustain and understandably fell into abeyance. Little real advance occurred for almost 50 years. Concepts of aetiology have meandered between those that invoked cornflakes, toothpaste, or a more general food allergy on the one hand, and the more scientifically respect- able possibilities of viruses and autoimmunity on the other.