In multidrug-resistant (MDR) tuberculosis, the pathogen is resistant to the two most important tuberculosis drugs, rifampicin and isoniazid, and standard therapy is therefore not effective. The diagnosis and treatment of MDR tuberculosis is more difficult and sometimes lengthy. Other drugs have to be used, which are often more expensive, sometimes less effective and can have more side effects. Treatment ranges from 6 months to 20 months and should be carried out by specialized doctors. The chances of recovery are slightly worse than with tuberculosis without multidrug resistance. In Germany, however, a disease with multidrug-resistant tuberculosis can often be treated successfully.
Like drug-sensitive tuberculosis, MDR tuberculosis is transmitted by aerosols containing bacteria and often affects the lungs, but can also affect all other organs. Multidrug-resistant tuberculosis can develop if it is treated with too few or the wrong drugs or if these are taken for too short a time or in too low a dose. However, direct infection with a multi-resistant pathogen is also possible.
In Germany, a multidrug-resistant form is found in around 3-6% of tuberculosis cases.