Background. Multidrug-resistant (MDR) tuberculosis, defined as a disease caused by Mycobacterium tuberculosis
strains,which are resistant tomore antituberculous drugs (at least to isoniazid and rifampicin), is a problemfrequently
discussed in the Czech Republic. Cases of specific disease refractive to causal antituberculous therapy are associated
with the risk of the spread of the causative agent among the population.
Methods and Results. The National Reference Laboratory for Mycobacteria collected 2813 Mycobacterium
tuberculosis strains isolated by Czech mycobacteriological laboratories in 1999 to 2001. All strains were tested for
susceptibility to basic antituberculous drugs and then theMDR strains were further tested for susceptibility/resistance
to other antituberculous and antibacterial drugs. TheMDR strainswere studied byDNAanalysis (DNAfingerprinting
restriction analysis, RFLP – Restriction Fragment Length Polymorfism) as well. Thirty-nine patients who had MDR
tuberculosis were excretors of 56 Mycobacterium tuberculosis strains. In average, MDR tuberculosis accounted for
1.96 % (1,7–2,4) of all cases of bacillary tuberculosis. The most frequent type of the multidrug resistance was that
resistant to four basic antituberculous drugs (isoniazid, rifampicin, ethambutol and streptomycin). It was confirmed
in 48.2 % multidrug resistant strains.
Conclusions. Isepamicin, clofazimin, capreomycin and amikacin are considered to be the most promising antituberculosis
drugs. Based on RFLP profiles, 61.5 % of strains were placed into 8 clusters while the other strains
remained unclustered. No significant differences in geographical distribution and population structure were found
between the excretors of clustered strains and those of unclustered strains. Preliminary comparison with restriction
profiles of the MDR Mycobacterium tuberculosis strains in the international database suggests the uniqueness of
Czech strains showing the profiles not found elsewhere to date.
Mycobacterium tuberculosis, multidrug-resistant tuberculosis (MDR TB), susceptibility testing, antituberculous
drugs, Restriction Fragment Length Polymorphism (RFLP).