Pathogenesis Tuberculosis infection is acquired by inhaling droplet nuclei containing microorganisms aerosolized from untreated persons. The risk of transmission is remarkably lower once treatment has begun, even when sputum cultures continue to yield the microbe. Also, the duration of contact is important. Under ordinary circumstances, sustained exposure for at least 2 mo is required to [...]
TUBERCULOSIS An infectious disease caused by Mycobacterium tuberculosis. Remarkable progress has been made in the control of tuberculosis (TB) in the USA and other industrialized countries. The mortality rate for TB patients declined from about 200/100,000 population at the turn of the century to about 1.5/100.000 in the 1980s. However, since 1985 this steady downward [...]
Pathogenesis Microorganisms reach the tracheobronchial tree via four routes: (I) inhalation, (2) aspiration, (3) direct inoculation from contiguous sites, and (4) hematogenous spread. Inhalation and aspiration are much more frequently involved than the other two routes. Pneumonitis occurs when the normal defense mechanisms of the lungs arc overwhelmed or impaired. Two major factors predisposing to [...]
