2. Tuberculosis
Tuberculosis is a potentially
fatal contagious disease that can
affect almost any part of the
body but is mainly an infection
of The lung .
It is caused by a bacterial
microorganism “mycobacterium
tuberculosis “.
5. 5
• TB has affected humans
for millennia
• Historically known by
a variety of names,
including:
– Consumption
– Wasting disease
– White plague
– TB was a death
sentence for many
History of TB
6.
7. • Until mid-1800s, many believed TB was hereditary
• 1865 Jean Antoine-Villemin proved TB was contagious
• 1882 Robert Koch discovered M. tuberculosis, the
bacterium that causes TB
Module 1 – Transmission and Pathogenesis of Tuberculosis 7
Mycobacterium
tuberculosis
10. Mycobacterium Tuberculosis
Characteristics
• Gram positive
• Obligate aerobe
• No spore forming, non motile rod
• Mesophile
• Lipid rich cell wall contains mycolic acid
• Slow generation time 15 – 20 hours.
11. Causes and symptoms
Transmission.
Tuberculosis spreads by dro
plet infection. This type of tr
ansmission means that when
a TB patient exhales tiny
droplets of fluid containing
tubercle bacilli are released
into air.
Actual tissue damage is not
caused directly by the tubercle
bacillus, but by the reaction of the
person's tissues to its presence.
13. Remaining challenges: TB & NTM
• TB prevention: IPT, TB vaccine
• TB control: New molecular tools,
incl. better detection of drug resist.
• TB treatment: New regimen
• Shortened duration
• Less drug-drug interactions
• MDR-TB, XDR-TB
• NTM: which regimen for which
patient? Colonization vs. disease?
Treatment outcomes? Need to
reduce drug toxicity!
15. Symptoms
• They are –
• Fever, fatigue,
weakness, night
sweats, weight
loss.
• Coughing,
sneezing, blood in
the sputum of the
infected person.
16.
17. Diagnosis
• The diagnosis of TB is made on the basis of l
aboratory test results.
• Body fluids other than sputum can be used f
or culture. If TB has invaded the brain or spi
nal cord, culturing a sample of spinal fluid
will make the diagnosis .
19. TB Pathogenesis
• Pathogenesis is defined as how an infection
or disease develops in the body
• Every infected person has a potential to
infect 20 or 25 people in a day .
• Coughing, sneezing and talking each of these
act spread more than 3000 infective bacteria
in the air.
• Inhalation of these particles causes this
disease.
20.
21. TB PATHOGENESIS
LATENT TB INFECTION (LTIB)
• Occurs when tubercle bacilli are in the body, but
the immune system is keeping them under
control
• Detected by the Mantoux tuberculin skin
test (TST) or by blood tests such as
interferon-gamma release assays
(IGRAs) which include:
–QuantiFERON®-TB Gold test (QFT-G)
–QuantiFERON®-TB Gold In-Tube (QFT-GIT)
–T-Spot®.TB test (T-SPOT)
• People with LTBI are NOT infectious
22. LTBI vs. TB DISEASE
Latent TB Infection (LTBI) TB Disease (in the lungs)
Inactive, contained tubercle
bacilli in the body
Active, multiplying tubercle
bacilli in the body
TST or blood test results
usually positive
TST or blood test results
usually positive
Chest x-ray usually normal Chest x-ray usually abnormal
Sputum smears and cultures
negative
Sputum smears and cultures
may be positive
No Symptoms Symptoms Such As Cough, Fever,
Weight Loss
Not infectious Often infectious before
treatment
Not a case of TB A case of TB
23.
24. Transmission of tuberculosis
• It is a contagious disease which
spread through the air .
• When infectious person cough,
sneeze, talk or spit they propel
germs known as bacilli, into the
air.
• A person only needs to inhale a
small number of these germs to
get infected.
25.
26. TB Transmission
Types of Micro bacteria
• M. tuberculosis causes most TB cases in U.S.
• Mycobacterium that cause TB:
– M. tuberculosis
– M. bovis
– M. africanum
– M. microti
– M. canetti
• Mycobacteria that do not cause TB
– e.g., M. avium complex
• It is the image of bacilli germs under the microscopic
vision of the sputum of an infected person.
28. Treatment
DRUG THERAPY.
Most patients with TB can
recover if given
appropriate medication
for a sufficient length of
time .
Three modern drug
treatments of TB :
Lower the number of bacilli
as quickly as possible .
Preventing the development
of drug resistance
Long term treatment to
prevent relapse.
29. Drugs usage –
• First line drugs - Isoniazid , Rifampicin ,
pyrazinamide , ethambutol .
• Second line drugs ( more toxic and less
effective) – Kanamycin , Ethionamide ,
Ofloxacin , Cycloserin.
• Noncompliance ( failure to complete the
course) – Directly observed therapy (DOT),
Health care workers observe medication.
30.
31. Tuberculosis prevention methods
• The most important steps are –
• First, early detection of patients who may have tuberculosis.
• Stay home. Don't go to work or school or sleep in a room with
other people during the first few weeks of treatment for active
tuberculosis.
• Ventilate the room. Tuberculosis germs spread more easily in small
closed spaces where air doesn't move. If it's not too cold outdoors,
open the windows and use a fan to blow indoor air outside.
• Cover your mouth. Use a tissue to cover your mouth anytime you
laugh, sneeze or cough. Put the dirty tissue in a bag, seal it and
throw it away.
• Wear a mask. Wearing a surgical mask when you're around other
people during the first three weeks of treatment may help lessen
the risk of transmission.