It mainly affects the lungs, but it can affect any part of the body, including thr tummy, glands, bones and nervous system.

1. Mycobacterium tuberculosis
DR.V.JEYANTHI KUMARI
ASSISTANT PROFESSOR OF ZOOLOGY
A.P.C.MAHALAXMI COLLEGE FOR WOMEN
THOOTHUKUDI-628002

2. Introduction
• The organism responsible
for tuberculosis in man
was discovered in 1882 by
R.Koch.
• A.Calmette’s and Guerin’s
discovery in 1919 of the
live vaccine against
tuberculosis.
I.Morphology
• It belongs to Gram-
positive and is a slender,
straight or slightly curved
rod, 0.5-4µ in length.
• It may have terminal
swellings.
• The organisms are
nonmotile,
pleomorphous, and do
not form spores or
capsules.
• They stain poorly by the
ordinary methods but are
stained well with the
Ziehl-Neelsen method.

3. II.Cultivation
• The organisms grow on
selective media, eg.,
coagulated serum,
glycerin agar, glycerin
potato, glycerin broth,
and egg media.
• Visible growth appears
within 8-10days after
inoculation on glycerin
agar, but in 2-3weeks a
dry cream-coloured
pellicle is produced.

4. III.Toxin production
• It does not produce an
exotoxin.
• It contains toxic substances
that are liberated when the
cell decomposes.
• These organisms consist of
tuberculin substances
responsible for the diseases.
•
• This is composed of the
proteins albumins and
nucleoproteins.
IV.Antigenic structure
• Mycobacterial antigens
produce agglutins,
opsonins, precipitins, and
complement-fixing bodied
in low titres.
• Tuberculin is considered to
be a peculiar antigen
(hapten).
• Tuberculin is widely used for
allergic tests, eg., the
pirquet reaction and
Mantoux test in human
beings.
• These tests are employed
for the determination of
infection with
M.tuberculosis.

5. V.Pathogenesis and disease
in man:
• It has been shown that
tuberculosis in human
beings is caused by two
types of mycobacteria.
They are
• 1. The human type-
M.tuberculosis
• 2. The bovine type-
M.bovis
• Infection with
tuberculosis takes place
through the respiratory
tract by the droplets and
dust, and, sometimes
through contaminated
foodstuffs, through the
skin and mucous
membranes.
• From the lungs it spreads
throughout the body,
causing generalized
infection.

6. VI.Immunity
• Man is naturally resistant to
tuberculosis.
• Active immunization -
Intracutaneous
immunization and
revaccination of BCG are
very effective.
• It enters the body through
inhalation.
• It gets lodged in pulmonary
alveoli.
• Alveoli phagocytes engulf
them.
• The bacilli multiply
intracellularly and are
carried to various parts of
the body.
• This bacterium does not
produce any toxin, but due
to rapid growth, the tissues
are consumed.
• In children, primary
infection leads to primary
complex. The adult type of
tuberculosis is due to the
reactivation of the primary
infection.

7. VII.Laboratory diagnosis
• Bacillus in the lesions by
microscopy.
• isolating it in pure
culture, or transmitting
the infection to
experimental animals.
• Demonstration of
hypersensitivity to
tuberculoprotein is of
some diagnostic value
Mantoux test
• In this test, 0.1ml of PPD
(Purified Protein
Derivative) containing
5TU (tuberculin units) is
injected intracutaneously
on the forearm, using a
tuberculin syringe.
• The site is examined 48-
72 hours later and the
diameter of induration is
measured. Erythema is
not taken into account.

8. • Induration of diameter
10mm or more is
considered positive.
• The measure of 5mm or
less is considered
negative.
• The measure of 6-9mm is
considered doubtful

9. VIII.Treatment
• Chemotherapy is more
effective.
• Bactericidal drugs like
rifampicin, isoniazid,
pyrazinamide,
streptomycin, and
bacteriostatic drugs such
as ethionamide, para
aminosalicylic acid, and
cycloserine are used.
IX.Epidemiology
• Low socioeconomic
status and malnutrition
are important features.
Dusty occupation,
exposure to silica dust
favour tuberculosis.
• Inhalation of
contaminated air is the
principal mode of
infection.

10. • X.Prophylaxis
Adequate nutrition, good housing, and health
education reduce the occurrence of tuberculosis.
Injection of BCG produces an immunity that lasts for
10-15 years. The latter consist of early detection and
treatment of cases, chemoprophylaxis, and
immunoprophylaxis.