The New-England Journal of Medicine recommends that MDR-TB be treated with no less than for drugs and ideally seven. These all have there own costs, schedules, and side effects. There is a good deal of room to error and worsen the strains resistance.
In short it is impratcal to treat this disease and would take a toll on the finances and health (in the way of side-effects) of the patient. This would compound the issues already at hand; it is a more difficult regimen to follow. Prevention must be the answer to MDR-TB–and for that matter, TB in general.