One third of the world population is infected with tuberculosis (TB), and new infections occur at a rate of one per second. The recent increase in the emergence of drug-resistant strains of Mycobacterium tuberculosis and the dearth of anti-TB drugs is threatening the future containment of TB. New drugs or delivery systems that will stop the spread of TB and slow down or prevent the development of drug-resistant strains are urgently required. One of the reasons for the emergence of drug-resistant strains is the exposure of mycobacteria to sub-therapeutic levels of one or more antibiotics. Lung lesions containing large numbers of bacteria are poorly vascularized and are fortified with thick fibrous tissue; conventional therapy by the oral and parenteral routes may provide sub-therapeutic levels of anti-TB drugs to these highly sequestered organisms. Administering drugs by the pulmonary route to the lungs allows higher drug concentrations in the vicinity of these lesions. Supplementing conventional therapy with inhaled anti-TB therapy may allow therapeutic concentrations of drug to penetrate effectively into lung lesions and treat the resident mycobacteria
