Pulmonary Tuberculosis Part 1

Objectives
• What is Tuberculosis?
• Type of Tuberculosis
• Mode of Spread of TB
• Clinical Presentation of Pulmonary TB
• Pathology of Pulmonary TB
• Diagnosis
• Differential Diagnosis
• Management
Website:medishared.org

What is Tuberculosis?
Tuberculosis = Tubercule + Osis
– Tubercule : a small nodular lesion in the
lungs or other tissues
– Osis : a process or condition
“Tuberculosis is a condition which causes a
small nodular lesions in the lungs & other
tissues”
Tuberculosis is an infectious disease caused
by Mycobacterium Bacteria.

Type of Tuberculosis
• Pulmonary Tuberculosis:
1) According to Culture
– Drug Sensitive Tuberculosis
– Drug Resistant Tuberculosis : MDR, XDR, TDR
2) According to AFB Smear
- Sputum Smear Positive Pulmonary TB
- Sputum Smear Negative Pulmonary TB
• Extrapulmonary Tuberculosis (EPTB)

Mycobacteria
• Aerobic
• Motile Except M.Marinum
• Acid Fast Bacilli
• Slow generation time:15-18 hours
• Classification:
1) Slow Growing, Intermediate growing &
Rapid growing
2) Tuberculous & Non-Tuberculous
Mycobacteria that form colonies clearly visible to the naked
eye within seven days on subculture are termed rapid
growers, while those requiring longer periods are termed
slow growers

• Mycobacteria can be classified into several major
groups for purpose of diagnosis and treatment.
– M. tuberculosis complex : M. tuberculosis, M.
bovis, M. africanum, and M. microti
– M. Leprae which are causative agents of human
and animal tuberculosis.
– Nontuberculous mycobacteria (NTM) : They are all
the other mycobacteria, which can cause
Pulmonary disease resembling tuberculosis &
Extrapulmonary Tuberculosis like lymphadenitis,
skin disease, or disseminated disease.

Tuberculosis is a Global Problem…
• TB is a treatable and curable disease
• TB occurs in every part of the world
• 3 million deaths due to TB every year
• Tuberculosis (TB) is second only to HIV/AIDS as the
greatest killer worldwide due to a single infectious
agent.
• HIV-induced immune suppression increases the risk
of progression to active TB nearly 100-fold

Pulmonary Tuberculosis
• Pulmonary Tuberculosis is a disease of lung
caused by Mycobacteria.
• Most Commonly caused by M.Tuberculosis
• In few patients, NTM causing Pulmonary
tuberculosis and Its only diagnosed by sputum
culture on L.J Media

• TB is a leading killer of HIV-positive people
causing one fourth of all HIV-related deaths.
• Over 95% of TB deaths occur in low- and middle-
income countries, and it is among the top 5
causes of death for women aged 15 to 44.
• About one-third of the world's population has
latent TB, which means people have been
infected by TB bacteria but are not (yet) ill with
the disease and cannot transmit the disease.

• People infected with TB bacteria have a lifetime
risk of falling ill with TB of 10%.
• Persons with compromised immune systems,
such as people living with HIV, malnutrition or
diabetes, or people who use tobacco, have a
much higher risk of falling ill.

10% chance that a
latent infection will
progress to TB
disease.
50% death
rate for these active
TB cases
if untreated.
90% of
those infected with M.
tuberculosis have
asymptomatic, latent
TB infection (LTBI)
Website : medishared.org

Clinical Presentation
85% of patients with TB present with
pulmonary complaints. Extrapulmonary TB i.e
Pleural effusion can occur with Pulmonary TB
• Cough with expectoration since 2 weeks
• Low grade evening rise fever
• Haemoptysis
• Loss of Appetite
• Loss of Weight
• Fatigue
• Chest Pain

Why Evening Rise Low Grade Fever?
• In TB cytokines specifically IL-1 level is markedly
increase that leads to fever, but as cortisol level is
also high than normal it counteract the action of IL-1
& as a result fever remains low grade.
• Due to Exaggerated Diurnal Variation, cortisol effect
is very high in late night while very less in
evening onwards that leads to evening rise of
temperature & night sweating.
• Normal diurnal variation of body temperature also
play a role to make this change more prominent.

Transmission
• When a person who is sick with active disease,
coughs, sneezes, or laughs will release infected
droplets in atmosphere.
• Inhalation of Infected Aerosols of 1-5 microns
which small enough to traverse the upper
respiratory defenses and deposit deep in the lung
(alveoli).
• Large droplets tend to lodge in the more proximal
airways and typically do not result in infection.

• Single cough can generate 3000 infective droplets,
with as few as 10 bacilli needed to initiate
infection.
• The organisms grow for 2-12 weeks, until they
reach 1000-10,000 in number, which is sufficient to
elicit a cellular immune response that can be
detected by a reaction to the tuberculin skin test.

RISK FACTORS
• A healthy immune system can often successfully
fight TB bacteria, but your body can't mount an
effective defense if your resistance is low. Diseases
and medications can weaken your immune
system, including :
• HIV/AIDS
• Diabetes
• Chemotherapy
• Malnutrition
• Advanced age
• Immunosuppressive medications

TB infection begins when the mycobacteria
reach the pulmonary alveoli, where they
invade and replicate within the endosomes of
alveolar macrophages.
Stage 1
tubercle bacilli

Lymphocytes and fibroblasts are among the cells that
aggregate to form granulomas surrounding the
infected macrophages To prevents dissemination of
the mycobacteria & provides a local environment for
interaction of cells of the immune system.
Stage2
granulomas

•Bacteria inside the granuloma can become dormant,
resulting in a latent infection.
•Another feature of the granulomas of human
tuberculosis is the development of abnormal cell death
(necrosis) in the center of tubercles. To the naked eye
this has the texture of soft white cheese and is termed
caseous necrosis.
Stage 3

The caseous centers of the tubercles liquefy, and the
organism begins to rapidly multiply extracellularly.
After time, the large antigen load causes the walls of
nearby bronchi to become necrotic and rupture. This
results in cavity formation.
Ghon complex is readily visible upon chest X-ray.
caseous necrosis.

Milliary or extrapulmonary stage is the
hematogenous spread of MTB .
“Milliary" is derived from the fact that
metastasizing tubercles are about the same size
“millet seed”.
Two types of lesions caused by milliary TB:
I. Exudative lesions result from the
accumulation of PMN's around MTB.
Here the bacteria replicate with virtually
no resistance. formation of a "soft
tubercle".
II. Productive “granulomatous” lesions occur
when the host becomes hypersensitive to
tuberculoprotein. formation of a "hard
tubercle".
Stage 4

Pulmonary Tuberculosis Part 1

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Pulmonary Tuberculosis Part 1