Tuberculosis is a severe and potentially lethal bacterial infection caused by Mycobacterium Tuberculosis. It primarily affects the lungs, but may also affect other parts of the body. While Tuberculosis was previously decreasing in the western world over the course of the last century, it has during the past decades started to increase again. Globally, tuberculosis is a significant problem and is the type of bacterial infection responsible for the highest number of deaths in adults. Individuals with impaired immune system are particularly susceptible to infection, why there is a large co-morbidity in patients affected by HIV. Globally it is estimated that approximately 8 million people will develop active disease on a yearly basis and 1.7 million will die from the disease every year.
Multi-drug resistant tuberculosis (MDR-TB) is defined as infection by a strain of mycobacterium tuberculosis, resistant to at least two of the first-line anti-tuberculosis medications. It complicates and limits the possibility to cure the affected individuals and to prevent spread of the disease in the society. Like for other bacteria, resistance develops when the levels of antibiotics in the affected patients are insufficient to kill all the bacteria, which may be caused by poor compliance to the treatment regimen for example due to lack of medication or funding. In recent years, bacterial strains with very broad resistance pattern to many antibiotics (extensively drug resistant (XDR-TB)) have started to emerge and are of particular concern. XDR-TB currently accounts for approximately 10% of MDR-TB world-wide.
MDR-TB should be treated with a combination of several anti-tuberculosis medications, often up to five different substances and usually for a period of up to two years, in order to secure complete eradication of the bacteria and prevent further development of resistance. Left untreated, MDR-TB has a mortality rate of as high as 80%. MDR-TB is considered a major threat to global public health by the WHO, which currently estimates approximately 0.5 million new cases of MDR-TB are reported each year, the vast majority of which in the developing world. Over the past decade, MDR-TB has become an increasing problem also in the EU and the Nordic countries, partly linked to immigration.