IS6110 FINGERPRINTING OF DRUG-RESISTANT MYCOBACTERIUM-TUBERCULOSIS STRAINS ISOLATED IN GERMANY DURING 1995

The epidemiological relatedness of drug-resistant Mycobacterium tuberc ulosis strains isolated in Germany in 1995 was evaluated by the standa rdized IS6110 fingerprinting method. Altogether, 196 M. tuberculosis i solates from 167 patients were analyzed. A large degree of IS6110 poly morphism was found, ranging from 1 to 20 copies. Multiple isolates fro m one patient generally remained stable over a period of up to 1 year. However, one strain showed an additional fragment 7 months after the first isolate was obtained. Isolates from 55 patients (33%) showed ide ntical fingerprint patterns or fingerprint patterns that differed only in one band, and thus they were clustered in 22 fingerprint groups. S pecific transmission links could be established between members of fou r groups, e.g., transmission by family contacts. In one case, transmis sion of a multidrug-resistant strain to a patient initially infected w ith a drug-susceptible strain could be shown. Besides these fingerprin t groups, 30 of the 167 isolates (approximately 18%) could be grouped in two fingerprint clusters,vith a similarity of at least 78%. Approxi mately 60% of the patients of these two clusters were known to be immi grants from the former Soviet Union, and one patient is still living i n Belarus. In conclusion, our results indicate that (i) transmission o f drug-resistant strains contributes substantially to the emergence of drug-resistant tuberculosis in Germany and (ii) drug-resistant M. tub erculosis strains were presumably carried over from the former Soviet Union to Germany by immigrants.