Metabolism ofMycobacterium tuberculosis

Potency of extracts of selected plant species from Mbeere, Embu County-Kenya against Mycobacterium tuberculosis

“…Without a known reservoir outside man, inhalation of aerosolized droplets containing infectious M. tuberculosis remains the predominant route of infection thus making pulmonary tuberculosis the prevalent form of infection (Glickman and Jacob, 2001). The tubercle bacilli are characterized by slow growth, dormancy, intracellular pathogenesis, genetic homogeneity, a complex cell envelope containing mycolic acid in their cell wall which makes them acid fast with a distinctively slow rate of division (~24 h) (Wheeler and Ratledge, 1994;Cole et al, 1998;Lawn and Zumla, 2011). These attributes enable it to persist in latent state for extensive periods of time, but perhaps more important accounts for the chronic phase of the disease.…”

Iron Metabolism

“…siderophores produced by foreign (non-mycobacterial) microorganisms, can also occur. Unpublished work from the author's laboratory had indicated that ferrirhodotorulic acid could act as an iron source for M. smegmatis (see Wheeler & Ratledge 1994) and recent work by Matzanke et al (1997) has shown that not only can rhodotorulic acid (a siderophore from yeasts) be used by M. smegmatis and M. fortuitum but also ferricrocin (from Aspergillus viridi-nutans), serratiochelin (from Serratia marcescens) and myxochelin (from a Myxobacterium). Some stimulation of growth was found with ferrioxamine B and rhizoferrin but not with aerobactin or enterobactin.…”

“…Although it can be argued (see Wheeler & Ratledge 1994) that the amounts of mycobactin found in mycobacteria grown in the laboratory are due to nothing more than the contrived continuous withholding of iron from the cells, nevertheless it must be supposed that some mycobactin will be produced when the cells grow in vivo. (It is hardly likely that mycobactin biosynthesis only occurs in mycobacteria grown in laboratory media.)…”

The emerging role of gasotransmitters in the pathogenesis of tuberculosis

“…Mtb physiology is unique as studies have shown that Mtb can survive for up to 12 years in sealed tubes and remain fully virulent [10]. During infection Mtb is exposed to a wide range of host substrates including organic acids, virtually all amino acids, nucleic acid precursors, nucleotides, lipids and numerous carbohydrates [11]. Thus, it is clear that Mtb must adjust its metabolism in response to the availability of environmental nutrients during the different stages of infection.…”