Choice of drugs. All of the studies below have tested the use of antibiotic drugs for the treatment of Crohn's Disease. The drugs chosen are ones that are known to be effective against well known mycobacterial infections, such as tuberculosis or leprosy. It is theorised that Crohn's disease is caused by mycobacteria that live inside host cells, i.e. they are intracellular mycobacteria. Hence, to be effective against them, the drugs chosen must have intracellular activity.
Few antibiotics have intracellular activity.
It is only in recent years that antibiotics have been developed that are active against intracellular mycobacteria. These antibiotics are known as macrolide antibiotics. One of these macrolide antibiotics is clarithromycin, which has been shown to be effective in treating Mycobacterium avium intracellulare , an intracellular mycobacterium that commonly infects immuno-compromised AIDS patients. When treating mycobacterial diseases, it is important to use multi-drug regimes. The reason for this is that mycobacteria have the ability to develop resistance to inividual drugs.