[Epidemiology of drug-resistant tuberculosis: world--Europe--Poland]

The phenomenon of drug resistance in tubercle bacilli (Mycobacterium tuberculosis) has been recognized since the early years of chemotherapy of tuberculosis (TB). However it was not until the mid-1990s, that the magnitude of the problem was highlighted by the first global report of the World Health Organization on the prevalence of anti-TB drug resistance. Up to now, four such reports have been released. Not only have they shown that drug resistance is present worldwide, but they have also demonstrated its expansiveness and a high tendency for progression. The two most detrimental forms of drug-resistant TB are multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB. Whereas MDR-TB implies resistance to at least isoniazid and rifampicin, the most potent drugs in the first-line regimen, XDR-TB is defined as MDR-TB with resistance to any of the fluoroquinolones and any of the second-line injectable drugs (amikacin, kanamycin, or capreomycin). The emergence and spread of drug-resistant TB are among the key factors contributing to the persistence of TB within the human population. This article outlines the current epidemiological status of drug-resistant TB in the world, Europe, and Poland.