European Society of Mycobacteriology - Instituto Nacional de Saúde ...

OP-20
GROWTH PROFILE OF CLINICAL ISOLATES OF Mycobacterium
tuberculosis COMPLEX IN MURINE MACROPGHAGES
Susanne Homolka 1 , Stefan Niemann 1 , David G. Russell 2 and Kyle H. Rohde 2
1 - Molecular Mycobacteriology, National Reference Center of Mycobacteria, Borstel Germany
2 - Department of Microbiology/Immunology, Cornell University, Vet. Med. Center, Ithaca, USA
Background
Mycobacterium tuberculosis and other members of the Mycobacterium tuberculosis complex (MTC) remain a major cause of
morbidity and mortality worldwide. Several studies based on spoligotyping, IS6110 fingerprinting and MIRU-VNTR typing
demonstrated that the global population structure of MTC is defined by phylogeographical lineages and genotypes that are
also associated with pathogenic differences. However, the influence of strain genomic variation on the outcome of infection
and the clinical presentation are not completely understood. In our study, we investigated growth differences of 15 strains
of five different genotypes in comparison to the CDC1551 reference strains in liquid culture and in macrophages.
Methods
Murine bone marrow derived macrophages were infected with liquid culture of different clinical isolates (MOI 3:1;
2x10 6 CFU/ml). Survival of strains in resting and activated macrophages was determined at different time points up to 11
days post-infection. Additionally, growth kinetics of all strains in 7H9 liquid media were analyzed.
Results
Growth analyses of clinical isolates in liquid culture based on OD measurements showed no significant differences in
comparison to CDC1551. However, we observed both strain- and genotype-specific survival and growth profiles within
resting and activated macrophages.
Conclusions
The genomic diversity of clinical isolates influences the complex interaction of the pathogen with host phagocytes.
Further analyses to correlate intracellular gene expression profiles with the outcome of infection are in progress.
62 ESM 2009