ABSTRACT
Mycobacterium tuberculosis (Mtb) is a non-motile, non-sporulating, strict aerobe, acid-fast rod that usually shows up unstained with Gram stain but, like all mycobacteria, appears stained with arylmethane dyes such as carbolfuchsin and rhodamine. The bacteria were assumed to be found initially in soil and some species evolved to live in mammals. The migration of a mycobacterial pathogen from domesticated cattle to humans and its adaptation to a new host by evolution to the closely related Mycobacterium tuberculosis was thought to take place within 10,000–25,000 years ago. Tuberculosis is a disease that is almost exclusively transmitted by aerosolized droplets containing infectious Mtb. Infection occurs after inhalation of droplet nuclei containing tubercle bacilli that traverse the mouth or nasal routes, upper respiratory tract and bronchi down to the alveoli of the lungs. The use of molecular techniques should be incorporated into public health systems for urgent and correct diagnosis.
