Emergence and transmission of second line drug resistant Mycobacterium tuberculosis complex strains in Germany

Aims: Drug resistant tuberculosis (TB) has become a serious challenge for global TB control. High rates of resistant and multidrug resistant (MDR, resistance to at least isoniazid and rifampin) M. tuberculosis complex (MTBC) strains have been documented in several “hot spot“ areas around the world. Additionally, increasing rates of second line drug resistance have been reported and an outbreak of an extensively resistant (XDR, defined as MDR plus resistance to any fluoroquinolone and injectable drugs) strain in South Africa has attracted world wide attention. Therefore, representative data on the prevalence and spread of second line drug resistant TB are urgently needed to develop more effective TB control strategies.

Methods: Second line drug resistance testing and molecular typing (IS6110 DNA fingerprinting and spoligotyping) will be performed for MDR strains.

Results: In the study period, more than 700 MDR strains were notified at the NRC. So far, a significant number of second line drug resistant strains could be determined. In year 2005, 40% of the MDR strains showed additional resistance to prothionamide, 10% were additionally resistant to amikacin, and 12% showed additional resistance to capreomycin. DNA fingerprinting revealed that an increasing number of strains belonged to the Beijing genotype. Transmission of second line resistant strains could be documented. Further analyses are in progress.

Conclusions: Our preliminary data already documented a significant number of second line drug resistance among MDR strains investigated. The Beijing genotype, which has been shown to be a major cause of resistant TB in several high incidence settings, is also frequent among MDR strains from Germany.