Similarities between Crohn's disease and mycobacterial disease.

Intestinal tuberculosis, a known mycobacterial disease, and Crohn's disease exhibit extremely similar symptoms. The following is a list of tables that gives a detailed comparison of the two diseases, and other mycobacterial diseases, on a clinical basis, a pathologic basis, and a systemic basis.

This great similarity has given rise to confusion when diagnosing the diseases, with one disease often being misdiagnosed as the other. In areas of the world where tuberculosis is more prevalent, such as Asia, Crohn's disease is rare, and often mistaken for tuberculosis. In others area, mostly North America and Europe, Crohn's disease is often the diagnosis of choice. This choice is based primarily upon the ability to culture mycobacteria from biopsies of the patient, as tested by the acid-fast stain test. If acid-fast mycobacteria are found, the diagnosis becomes tuberculosis, otherwise it becomes Crohn's disease.

This confusion is contributed to by the fact that there is a degree of similarity between treatments of the two diseases. The correct course of treatment for tuberculosis is a lengthy, multi-drug regime of antibiotics, which results in improvement of the patient after some weeks. But, Crohn's disease patients that have been treated with these same drug regimes have also improved greatly. Crohn's patients treated with anti-tuberculosis regimes and Crohn's patients treated with anti-leprosy regimes went into remission. See the page "Anti-mycobacterial treatment and Crohn's Disease" for more details.

Similarly, tuberculosis patients treated with corticosteroids(e.g. Prednisone), usually used for treating Crohn's disease, experience a remission of symptoms for periods of up to two months. However, the disease invariably returns, and its symptoms are exacerbated after this initial remission. See "Case report: gastrointestinal tuberculosis simulating Crohn's disease." and "Synchronous intestinal, tonsillar and pulmonary tuberculosis."

The misdiagnosis between Crohn's disease and intestinal tuberculosis continues today. See the page Diagnostic confusion between Crohn's disease and intestinal tuberculosis. for a list of references.

The acid-fast test.

The most important criterion for diagnosing intestinal tuberculosis instead of Crohn's disease is the presence of "acid-fast bacilli" (bacteria that become visible when tested by Ziehl-Neelsen acid-fast staining). Both mycobacteria, tuberculosis and paratuberculosis, come in two forms, the bacillary and spheroplast forms. The spheroplast form of both is not dectectable by the acid-fast stain test. The bacillary form of tuberculosis is readily detectable by the acid-fast test. The spheroplast form of tuberculosis is known as hypertrophic tuberculosis, and the acid-fast test often fails to demonstrate mycobacteria in cases of this disease. It is theorised that Crohn's disease is caused by the spheroplast form of mycobacterium paratuberculosis, and thus not detectable by the acid-fast stain test.

Source: http://archive.crohn.ie/similar.htm
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