Sensitivity of mycobacteria to organic solvents, evaporation and antibiotics

Abstract

Mycobacterium tuberculosis causes 1.4 million tuberculosis deaths annually. This bacterium has a complex, lipid-rich cell wall which facilitates resistance to killing by various caustic reagents. Experiments in this thesis examine aspects of mycobacterial physiology. One study assessed mycobacterial resistance to organic solvents. Equal volume 5-minute extraction with methanol reduced aqueous phase viability of M. tuberculosis by 4.5-log10 CFU, while acetone resulted in a reduction of 2-log10 CFU. Another study examined whether drying spilled M. tuberculosis on a solid surface was bacteriocidal. Results indicated only a 2-log10 CFU reduction after 12 hours. A third line of research was to develop vectors for deleting two M. tuberculosis genomic targets regulated by a virulence-associated sigma factor. Plasmids specific for each target were generated, but conversion into specialized transducing phages was unsuccessful. The fourth study indicated that this sigma factor did not contribute to bacterial antibiotic tolerance in macrophages.