PULMONARY TUBERCULOSISShao LiThe department of respiratory of Ren-ji hospital
General Considerations • Tuberculosis is a chronic infection, potentially of lifelong duration, caused by two species of mycobacteria M.tuberculosis and, rarely, M.bovis • It was isolated by Robert Koch in 1882 • The morbidity and mortality of tuberculosis are high in developing countries.
The disease is confined to the lungs in most patients but may spread to almost any part of the body General Considerations
Etiology • The tubercle bacillus (M.Tuberculosis) is aerobie, non-motile,non-spore-forming, high in lipid content, and acid and alcohol-fast • It grows slowly . • It can’t tolerate heat, but It can live in humid or dry or cold surroundings.
epidemiology A key link of epidemic • The source of contagious • The route of spread • Peoples of easily affected
Tuberculosis is transmitted by airborne droplet nuclei(containing tubercle bacilli )
Many droplet nuclei are capable of floating in the immediate environment for several hours • Large particles may be inhaled by a person breathing the same air and impact on the trachea or wall of the upper airway
The transmission is determined • The probability of contact with a case of TB • The intimacy and duration of that contact • The degree of infectiouseness of case • The shared environment of the contact
Pathogenesis tubercle bacillus Human immunity
Human Immunity after infected tubercle bacillus and tuberculin hypersensitivity • The natural immunity of human to TB is nonspecific • After infected or given BCG vaccine, human will obtain specific immunity • The immunity of tubercle bacillus is cell- mediated immunity
Human Immunity after infected tubercle bacillus and tuberculin hypersensitivity • The cellular immunity develops within 4 to 8 weeks after infected with bacillus Many immunologic cells involve in the formation of pulmonary tuberculosis.
Two types of cells are essential in the formation of TB • Macrophages: directly phagocytize TB and processing and presenting antigens to T lymphocyte • T lymphocytes(CD4+): induce protection through the production of lymphokines
T lymphocytes(CD4+) • Many lymphokines are involved in tuberculosis, the interplay of these cytokines determine the hosts response for example • IL-1 is related to fever • IL-6 is related to hyperglobulinemia • TNF is related to the killing of mycobacteria formation of granolomas • other cytokines including IL-4,IL-5,IL-10 can promote humoral immunity
Genetic factors play a key role in innate nonimmune resistance to infection with M. Tuberculosis • These genes may have a role in determining susceptibility to tuberculosis
Koch phenomenon It refers that there is different reaction to TB infection between primary and secondary infection
During the course of TB, there are three basic pathologic changes • Including infiltration, hyperplasia, ulceration or calcification • These changes happen in different stage of tuberculosis • When host defense is destroyed and there is much more bacterias, caseating ulceration will exist • Otherwise, when host defense is predominant and there is less bacteria,perhaps hyperplasia and calcification will happen
The result of the tuberculosis after infection • Absorption • Fibrosis • Calcification • Deterioration: enlargement of infected aeras and appear newer infiltrated regions or spreading.
There are five common clinical patterns of tuberculosis 1. Primary pulmonary tuberculosis (Primary Complex and Bronchial Lymphnod-Tuberculosis) 2. Milliary Tuberculosis (acute, subacute and chronic hematogenous pulmonary tuberculosis) 3. secondary pulmonary tuberculosis Infiltrative pulmonary tuberculosis Chronic fibrocavenous pulmonary tuberculosis 4.Tuberculous pleuritis 5.Extrapulmonary tuberculosis
Clinical Manifestations • systemic signs: Most patients present as cases of pulmonary tuberculosis with fever, weight loss, anorexia, fatigue, night sweats wasting. • respiratory signs: Cough may vary from mild to severe, and sputum may be scant and mucoid or copious and purulent Hemoptysis may be due to cough of a caseous lesion or bronchial ulceration chest pain, tachypenea ect. Physical signs: nonspecific.
SpecificManifestations • Allergic reaction to TB • Non-reaction pulmonary tuberculosis
Laboratory and physical examinations • Chest radiography • Sputum examination • Tuberculin testing • PCR test to detect TB • TB antibody testing • bronchoscopy
Radiology • Chest radiography is the most important method to detect TB • TB’s characteristics of a chest radiograph favor the diagnosis of tuberculosis as following :
(1) shadows mainly in the upper zone (2) patchy or nodular shadows (3) the presence of a cavity or cavities, although these, of course, can also occur in lung abscess, carcinoma, etc (4) the presence of calcification. although a carcinoma or pneumonia may occur in an areas of the lung where there is calcification due to tuberculosis (5) bilateral shadows, especially if these are in the upper zones (6) the persistence of the abnormal shadows without alteration in an x-ray repeated after several weeks this helps to exclude a diagnosis of pneumonia or other acute infection
Milliary Tuberculosis acute milliary tuberculosis
secondary pulmonary tuberculosis infiltrate
Sputum examination There are direct smear and culture Direct smear examination is only positive when large numbers of bacilli begin to be excreted
Sputum examination • A negative smear by no means excludes tuberculosis • A negative smear in the presence of extensive disease and cavitation makes the diagnosis less likely. • Particularly if the negatives are frequently repeated
Tuberculin testing A positive tuberculin test although it is of great use in children, but it has limited diagnostic significance in older age groups
•A reaction of less than 5 mm is considered • negative • • 5-9 mm is considered positive (+) • • 10-19 mm is considered positive (++) • • more than 20 mm is considered positive • (+++) A positive tuberculin skin test indicates • tuberculous infection, with or without disease
White blood count and ESR • The white blood count is usually normal. • In practice the white blood count is only useful in a minority of cases, When the patient is less ill and the radiological shadowing less extensive the count is often normal or high normal ESR is often elevate
Diagnosis According to the history, clinical signs, chest X-rayand some other examinations, we can diagnose TB A patient with tuberculous pulmonary disease will come to the physician for one of three reasons: (1) Suggestive symptoms (2) A positive finding on routine tuberculin testing (3) A suspicious routine chest roentgenogram
How to write the diagnosis correctly? • Generally, we write the diagnosis according to the site of TB, clinical patterns, the result of sputum examination and the history of chemotherapy.
Differential Diagnosis 1 2 3 4 Bronchiectasis may confused with chronic fibrocavenous pulmonary tuberculosis. They also have chronic cough, sputum production and hemoptysis. Usually we can use chest x-ray examination and CT scan to distinguish them.
Differential Diagnosis1 2 3 4 Cavitary lung abscess often involves the dorsal segments of the lower lobes and posterior segments of the upper lobes. Typically lung abscess causes litt1e in the way of physical findings, may have a fluid level, and is not associated with patchy bronchogenic infiltrates. In contrast, physical findings are prominent over tuberculous cavities, fluid levels are rare. And patchy infiltrates elsewhere are the rule.
Differential Diagnosis 1 2 3 4 Acute bacterial pneumonias may resemble florid tuberculosis in all particulars except for the sputum examination and response to antimicrobial drugs.
Differential Diagnosis1 2 3 4 Neoplasm may resemble tuberculosis. As in an isolated coin lesion. An obstructing and inconspicuous endobronchial tumor causing distal cbronic inflammation or a caviting neoplastic mass. ( An irregular cavity wall suggests necorotic neoplasm. )
Differential Diagnosis1 2 3 4 5 • Fever caused by some other diseases
complications • Pneumothorax • Bronchiectasis • Empyema • Extrapulmonary expansion • Hemoptysis • Chronic pulmonary heart disease
Therapy • Chemotherapy • Support therapy • Surgical therapy
The metabolic state of tubercle bacilli • A groups • B groups • C groups • D groups
Treatment • The principles of antituberculous chemotherapy involve earlier, combination, appropriate , regularly and durations.
Treatment • The critical issue in TB control is adopting the DOTS (1995) ( Directly Observed Treatment, Short-course therapy; DOTS Strategy is recommended by the WHO TB Program.