On the Development of Mycobacterial Infections: I. A Review Concerning the Common Situation

Abstract

In this review concerning the common situation of mycobacterial infections the following problems are discussed: (1) The worldwide epidemiological situation of tuberculosis reveals an increase in the developing countries but even in some industrialized countries like the United States. The reasons for this development are mainly socioeconomic factors. (2) The association between tuberculosis and HIV infection has caused in general a marked increase in the incidence of tuberculosis in some countries. Because of its ability to destroy the immune system, HIV is a significant risk factor for the progression of tuberculosis infection as a clinical disease. Taking into account that 5 million persons worldwide are infected with tuberculosis as well as with HIV (most of them living in the Sub-Saharan Africa), enormous future problems can be anticipated. (3) The new fear of tuberculosis has resulted mainly from reports about outbreaks with multidrug resistant strains of Mycobacterium tuberculosis in the United States. These strains are at least resistant to the most important antituberculotic drugs isoniacid and rifampicin. The frequency of multidrug-resistant tuberculosis in the USA is reported to be overall 3-7%, however for New York 19% is estimated. The main reason for this development is inadequate chemotherapy mostly due to poor compliance. Therefore in the United States the directly observed therapy has been established. Complete and reliable reports of the resistance situation in other countries are not available because most of these have no resistance surveillance programs. (4) As immunocompromised patients become more numerous, the importance of nontuberculous mycobacteria has significantly increased. Mainly organisms of the Mycobacterium avium-intracellulare complex play a special role as opportunistic pathogens for AIDS patients in later stages of their disease. Therapy for these infections is problematic due to the high resistance of most ubiquitous mycobacteria to antituberculotic drugs. (5) New laboratory techniques have shortened the detection time (radiometric culture systems) and the time needed for the identification of the most important mycobacteria species (DNA probes). A further improvement of the laboratory diagnosis of tuberculosis is expected in the near future by nucleic acid amplification techniques (polymerase chain reaction and others).