Tuberculosis Disease

Tuberculosis – Clinical Features
Localized type may be asymptomatic
Low grade remittent fever, night sweats, malaise, anorexia, weight loss
Sputum at first mucoid and later purulent
Haemoptysis in half of the patients
Pleuretic pain

Tuberculosis – Diagnosis
History, physical examination, radiological findings “consolidation & cavitation”
Identification of the acid-fast bacilli in smears and culture of sputum “10 weeks”
PCR amplification of M. tuberculosis DNA

Tuberculosis – Prognosis
Depends on:
The extent of the disease and the patient immune status
Secondary amyloidosis may occur in persistent cases

Tuberculosis – Chronic Consequences
Pulmonary fibrosis
The lung lesions may heal with fibrosis at any stage, particularly with treatment
This ranges from minor apical scarring to extensive and severe widespread fibrosis producing localized to widespread honey-comb appearance of the lung tissue. It is particularly seen in relapsing and progressive untreated disease
This is complicated by respiratory failure & cor pulmonale
Pleural fibrosis
Fibrosis commonly obliterate the pleural space
Bronchiectasis
Damage to the bronchial walls and scarring can cause distal pulmonary collapse, secondary infection and bronchiectasis

Infection in Immunocompromised Individuals
Mycobacterial infection of all types are increased in immunocompromised individuals and is in most cases due to reactivation of latent infection
Features are similar to infection in immunocompetent individuals but disease usually progresses more rapidly due to decreased host response

Atypical Mycobacterial Infection
These infections are caused by a group of non-tuberculous mycobacteria of which the most important types are M. avium- intracellulare and M. kanasii
The organisms are widely distributed in soil, water & domestic animals
Infection is acquired directly from the environment and not by case to case contact
Infection by these organisms is seen in immunocompromised patients particularly AIDS
It can be seen also in immunocompetent individuals with chronic pulmonary disease

The lymph nodes in this mesentery, best seen at the left, are enlarged and have cut surfaces that appear yellow-tan. These nodes are filled with sheets of Mycobacterium avium-complex (MAC) organisms, and the immune response is so poor in this AIDS patient that there is no focal granuloma formation
Atypical Mycobacterial Infection – Gross Morphology

Microscopically, Mycobacterium avium-intracellulare infection is marked by numerous acid fast organisms growing within macrophages. Lots of bright red rods are seen, particularly in macrophages, in this acid fast stain of lymph node
Atypical Mycobacterial Infection – Microscopic Morphology