Lipid bodies in mycobacteria

A survey of clinical samples revealed that LBs are a universal feature of tubercle bacilli in sputum. A number of conditions including hypoxia, Nitric Oxide (NO) exposure, pH, heat and cold shock were shown to promote LB formation in M. tuberculosis in vitro. The formation of LBs in NO exposed M. tuberculosis was shown to correlate with the level of antibiotic tolerance displayed by the population. Antibiotic tolerance was thought to be a result of transitory growth arrest; however attempts to assess the growth status of LB positive M. tuberculosis cells were unsuccessful. The morphology of LBs in mycobacteria varied according to the growth condition of the cell and may be due to a change in lipid composition. The mechanism by which LBs are formed in mycobacteria remains unknown; however, there was some evidence to suggest that it follows a scheme similar to that which has been previously demonstrated in Rhodococcus opacus..;It was concluded that LB formation in mycobacteria may depend on a number of environmental factors, including conditions that promote growth arrest. The formation of LBs in M. tuberculosis may anticipate antibiotic tolerance. The presence of LBs in sputum tubercle bacilli may be used to assess treatment response in patients with tuberculosis; however, it remains to be shown that LB positive M. tuberculosis cells in vitro represent the physiological LB positive sputum bacilli.