Mycobacterium tuberculosis Characteristics Mycobacterium tuberculosis is a non-motile, acid-fast, obligate aerobe bacterium that resists decolorization with acidified organic solvents Considered hydrophobic due to the high lipid content in the cell wall It is not considered gram positive nor gram negative, but instead is classified as acid-fast M. tuberculosis is manifested more often in HIV positive patients due to a weakened immune system High resistance to drug therapy Contagious for several weeks after drug therapy is initiated http://www.turbosquid.com/3d-models/3d-mycobacterium-tuberculosis-model/683105 A. Ryan F2013 Modified by DYH

M. tuberculosis Virulence M. tuberculosis does not have the classical virulence factors Lipoamide dehydrogenase (Lpd) - helps the bacterium resist host-reactive nitrogen intermediates Antigen 85 complex: group of secretedproteins that bind fibronectin; may help in protecting the bacterium from the immune system Slow generation time: immune system may not readily recognize the bacterium and therefore not be able to kill it High lipid concentration of cell wall: enables the bacterium to be resistant to many antimicrobial agents, acidic and alkaline compounds, and osmotic lysis Cord factor: known to be toxic to humans and other mammalian cells http://medicineworld.org/images/blogs/11-2007/mycobacterium-tuberculosis-299290.jpg A. Ryan F2013 Modified by DYH