Tuberculous bronchopneumonia. Light micrograph of tissue from a lung in a case of tuberculous bronchopneumonia, a combination of tuberculosis (TB) and pneumonia. TB is a disease caused by infection with Mycobacterium tuberculosis bacteria. Bacterial pneumonia, which results in inflammation of the lung, is most commonly caused by the bacteria Streptococcus pneumoniae. A tubercle (site of TB infection) is at top right (round, solid pink). This tubercle formed after destruction of the wall of a segment of a bronchiole (airway, lower centre and centre).