ON THE DEVELOPMENT OF MYCOBACTERIAL INFECTIONS .2. CHANGING MYCOBACTERIAL INFECTION SPECTRUM IN THE COLOGNE AREA 1983-1993

The overall detection rate of mycobacteria in the Cologne area did not change between 1983 and 1993. But a significant shift of the rate of Mycobacterium tuberculosis to nontuberculous mycobacteria, especially Mycobacterium avium-intracellulare complex, could be observed. Whereas the portion of Mycobacterium tuberculosis fell during these years fro m about 90% to 50-70% the portion of Mycobacterium avium-intracellular e increased steadily from 0 to 23% of all mycobacteria positive patien ts. The portion of tuberculosis patients positive for HN remained cons tantly at 5-7% until 1992. Whether the 10% in 1993 signalizes a defini tive increase remains to be proven. HIV positive patients with the dia gnosis mycobacteria show another development. Whereas Mycobacterium tu berculosis is isolated constantly from about 2-3% of all HN positive p atients, the Mycobacterium avium-intracellulare complex increased from 0 to 10%. As methodical factors play a special role in the diagnostic procedure of mycobacteria, we evaluated some of the newer techniques for our routine laboratory: The well-known high sensitivity and specif icity of the DNA probes (Gen-probe system) was confirmed, and by the r adiometric culture system, in fact, the ubiquitous mycobacteria were d etected much better. Otherwise from one third of special materials Myc obacterium tuberculosis and Mycobacterium bovis grew only on the conve ntional solid media. The susceptibility testing of 925 Mycobacterium t uberculosis strains revealed a rate of 10% (95 strains) with resistanc e to one antituberculotic drug only and 3% (29 strains) with resistanc e to two or more drugs. Only 0.9% (8 strains) were resistant to isonia cid and rifampicin (multidrug-resistant strains) indicating that drug resistance of Mycobacterium tuberculosis is still no serious problem i n our region.