Das langsame Wachstum von Mykobakterien

A characteristic feature of mycobacteria is their slow growth rate, which in addition strongly varies in different species of the genus. All highly pathogenic species such as M. tuberculosis and M. leprae causing tuberculosis and leprosy, respectively, belong to the slow growing mycobacteria, while the apathogenic and opportunistic species are members of the fast growing mycobacteria. This suggests that the question be posed whether there is causality between mycobacterial growth rate and virulence. We discuss possible reasons for the slow and variable growth rates of mycobacteria and the current state of knowledge concerning the significance of slow growth for mycobacterial pathogenicity.

Use of a quantitative TaqMan-PCR for the fast quantification of mycobacteria in broth culture, eukaryotic cell culture and tissue

The quantification of slow-growing mycobacteria such as Mycobacterium tuberculosis or M. bovis from in vitro and in vivo samples is complicated by their long generation time, their ability to form aggregates, and their capacity to persist in a state of dormancy. We compared different methods for the establishment of growth curves for broth cultures of M. bovis bacille Calmette-Guérin (BCG). A quantitative TaqMan-PCR yielded results comparable with those obtained by protein quantification and measurement of the ATP content of the cultures. The quantitative TaqMan-PCR furthermore turned out to be particularly suitable for the measurement of multiplication of BCG within eukaryotic cells. Furthermore, it is a fast method allowing an estimation of the mycobacterial load in tissue long before colony counts can be obtained.