t.b. patho

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    Pathophysiology of

    Tuberculosis

    Pratik Godhani

    Pharmacy Management.

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    Introduction

    Tuberculosis (TB) is a communicable infectious disease caused

    by Mycobacterium tuberculosis. It can produce latent

    infection as well as progressive, active disease.

    M. tuberculosis is transmitted from person to person bycoughing or sneezing or close contacts of TB patients.

    WHO

    13 million chronic active cases + 9.3 million new cases

    (3.4 million cases in India only)

    T.B. occurs at rate of one per second.

    Market of Anti tuberculosis drugs and vaccines by 2011 is

    expected to reach 670 million USD.

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    Mycobacterium tuberculosis is spread by small airborne

    droplets, called droplet nuclei, generated by the coughing,

    sneezing, talking, or singing of a person with pulmonary or

    laryngeal tuberculosis.

    Introduction ofM tuberculosis into the lungs leads to infection

    of the respiratory system.

    However, the organisms can spread to other organs, such as

    the lymphatics, pleura, bones/joints, or meninges, and cause

    extrapulmonary tuberculosis.

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    PATHOPHYSIOLOGY

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    Droplet nuclei with

    bacilli are inhaled, enter

    the lung, and deposit in

    alveoli.

    Macrophages and T

    lymphocytes act together

    to try to contain the

    infection by forming

    granulomas.

    In weaker immune systems, the

    wall loses integrity and the

    bacilli are able to escape and

    spread to other alveoli or other

    organs.

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    CLINICALPRESENTATION

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    Early infection :

    Immune system fights infection.

    Infection generally proceeds withoutsigns or symptoms.

    Patients may have fever, paratracheallymphadenopathy, or dyspnea. Infectionmay be only subclinical and may notadvance to active disease.

    Early primary progressive :

    Immune system does not control initialinfection.

    Patients often have nonspecific signs orsymptoms (eg, fatigue, weight loss,fever).

    Nonproductive cough develops.Diagnosis can be difficult: findings onchest radiographs may be normal and

    sputum smears may be negative formycobacteria.

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    Late primary progressive:

    Cough becomes productive.

    More signs and symptoms asdisease progresses. Patients

    experience progressive weight loss,rales, hemoptysis.

    Findings on chest radio -graph arenormal, may show cavity.Diagnosis:cultures of sputum.

    Latent:

    Mycobacteria persist in the body.Nosigns or symptoms occur.

    Patients do not feel sick. Patients aresusceptible to reactivation ofdisease.

    Infection can reappear whenimmunosuppression occurs.

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    DIAGNOSIS

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    TEST NAME DESCRIPTION

    RADIOGRAPHY Patchy or nodular infiltrates and Cavitation in the apical

    areas of the upper lobes or the superior segment of the

    lower lobes.

    SPUTUM CULTURE IDENTIFY M.Tuberculosis (4-7 days with HPLC)POLIMERASE CHAIN

    REACTION

    Identify M. tuberculosis, (1-2 hrs)

    TUBERCULIN SKIN TEST

    QUANTIFERON- TB TEST Measure immune reactivity to M.tuberculosis (12-14 hrs)

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    Chest radiograph shows

    presence ofCavitation in

    affected part of Lung

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    TUBERCULIN SKIN TEST

    Infection with M. tuberculosis produces a delayed

    hypersensitivity skin reaction to certain components

    of bacterium(purified protein derivatives PPD)

    Administer 0.1 ml volume containing 5 TU of PPD

    into top layers of skin of the forearm

    Reading after 48-72 hours of injection.

    Observe presence or absence of induration (localizedswelling).

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    Positive Tuberculin Skin Test:

    Diameter (mm) Considered positive for

    5

    Persons at high risk for tuberculosis:

    Patients with chronic diseases (e.g., infection with human

    immunodeficiency virus)Persons with recent exposure to tuberculosis

    Employees of hospitals and long-term care facilities

    10

    Persons at risk for tuberculosis:

    Injectable drug users, Persons in close living conditions

    Persons born in countries with high prevalence of

    Tuberculosis,Persons with following clinical conditions : silicosis;

    diabetes mellitus; chronic renal failure; some hematologic

    disorders (e.g., leukemias and lymphomas);

    15 Persons with no risk factors for TB

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    THANKYOU