Bacterial infections that are communicable, are very common in developing countries, in spite of availability of specific treatment, these diseases still continue to occur resulting in a number of deaths, or disabilities. In this section bacterial infections are discussed according to their priority. Tuberculosis is a chronic disease which mainly involves respiratory system because the infection is airborne. The disease is caused by a gram-positive bacterium known as Mycobacterium tuberculosis. The tubercle bacilli enter the respiratory system through inhalation of dust particles containing the bacilli. The infection should be treated effectively and the duration of the treatment varies from 6 months to 1 year depending upon the severity of the disease. BCG vaccination given to the children offers protection against childhood tuberculosis and its complications but does not offer protection against adult tuberculosis.