2. Introduction
TB is one of the oldest recorded
human afflictions
Still one of the biggest killers
among the infectious diseases
The bacillus causing tuberculosis,
Mycobacterium tuberculosis, was
identified and described on March
24, 1882 by Robert Koch
3. One-third of the
world's population is
currently infected with
TB
with 8 to 10 million new
cases each year.
2 million TB related
deaths/year
Epidmiology
Incidence and prevelance
4. M. tuberculosis
M. bovis
M. africanum
M. microti
M. canettii
M. caprae
M. pinnipedii
Etiology
Human tuberculosis (TB) is caused by
infection with members of the
Mycobacterium tuberculosis complex, which
includes :
5. Characteristics of M.tuberclosis
Slightly curved,rod shaped bacilli
Aerobic, Non motile
Thick lipid cell wall,resist
decolorization with acidified
alcohol
“ Acid fast bacteria”
Multiplies slowly”every 18 - 24 hrs”
Can remain dormant for decades
6. Person-to-person
through the air by a
person with TB
disease of the lungs
Less frequently transmitted by:
• Ingestion of Mycobacterium bovis
found in unpasteurized milk products
• Laboratory accident
How is TB Transmitted?
Source: CDC, 2000
7. The probability that TB will be transmitted
from one person to another depends on a
number of factors
The concentration of TB bacteria in the air
The environment in which exposure to the
bacteria occurs
The length of time of exposure
Person‘ s immune system
8. Risk factors
Co infection with HIV
Diabetic person
Persons undergo chemotherapy
Person undergo organ transplantation
Extreme ages,children and geriatric
Malnutration
14. Active TB Disease
Germs:
Awake and multiplying
Cause damage to the lungs
Person:
Most often feels sick
Contagious (before pills started)
Usually have a positive
tuberculin skin test
Chest X-ray is often abnormal
(with pulmonary TB)
Granuloma breaks
down and tubercle
escape and multiply
TB
15. Germs:
Sleeping but still alive
Surrounded (walled off) by
body’s immune system
Person:
Not ill
Not contagious
Normal chest x-ray
Usually the tuberculin skin
test is positive
Latent TB infection(LTBI(
20. Diagnosis
Medical history
Physical examination
Sputum smear microscopy
Acid fast staining (Ziehl–Neelsen stain)
Fluorochrome stain using fluorescence microscopy
Culture
Immunological tests
TB skin test(Tuberculin skin test )
TB blood tests
Chest radiograph (X-ray)
PCR
21. Bacteriologic Examination of Clinical
Specimens
The bacteriologic examination has five
parts:
Specimen collection, processing, and review
AFB smear classification and results
Direct detection of M. tuberculosis in clinical specimen
using nucleic acid amplification (NAA)
Specimen culturing and identification
Drug-susceptibility testing
22. Specimen Collection, Processing, and
Review
At least three consecutive sputum
specimens are needed, each
collected in 8- to 24-hour intervals,
with at least one being an early
morning specimen.
If possible, specimens should be
obtained in an airborne infection
isolation (AII) room or other
isolated, well-ventilated area (e.g.,
outdoors)
24. Sputum smear microscopy
a. Ziehl-Neelsen stain
fixed smear covered with
carbol-fuchsin, heated, rinsed,
decolorized with acid alcoholb.
b. Fluorochrome stain with phenol-
auramine
modified acid alcohol step
potassium permanganate
counter staining; fluorescent
Mycobacteria visible with 20 or
40X magnification
SMEAR POSITIVITY
MEANS AT LEAST 10,000
ORGANISMS/mL SPUTUM
Fluorochrome stain
25. Culture (Gold Standard(
a. Solid media
Lowenstein Jensen (egg based)
Middlebrook 7H11 (agar based)
can detect colony morphology,
mixed infections; can detect 10-
100
organisms/mL; 3-8 weeks
incubation to detect organisms
b. Liquid broth
Middlebrook 7H12, BACTEC
systems
1-3 weeks of incubation to
detect organisms
M.Tuberclosis on
Lowenstein Jensen media
Buff colonies
26. TB skin test(Tuberculin skin test(
Called the Mantoux
tuberculin skin test
Result depends on the
size of the raised, hard
area or swelling
Also depends on the
person’s risk of being
infected with TB bacteria
and the progression to
TB disease if infected.
27. TB blood tests
(Interferon-Gamma Release Assays, IGRAs(
Measures how strong a person’s
immune system reacts to TB bacteria
Two IGRAs
QuantiFERON®–TB Gold In-Tube test (QFT-
GIT
T-SPOT®.TB test (T-Spot)
28. IGRAs are the preferred method of TB
infection testing for
People who have received bacille
Calmette–Guérin (BCG). BCG is a vaccine
for TB disease.
People who have a difficult time returning
for a second appointment to look for a
reaction to the TST.
TB blood tests
(interferon-gamma release assays, IGRAs(
29. TB treatment is challenging, requiring
accurate and early diagnosis,
drug‑resistance screening and the
administration of effective treatment
regimens for at least 6 months through
( Directly Observed Therapy (DOT) and
follow‑up support.
Treatment for tuberculosis (TB) depends
on which type you have, although a long
course of antibiotics is most often used
Treatment
30. The goals of TB treatment are to:
1. Shorten the clinical course of TB
2. Prevent complications
3. Prevent the development of latency
and/or subsequent recurrences
4. Decrease the likelihood of TB
transmission
Treatment
31. First-line anti-TB drugs
recommended in a four-drug
combination
for the treatment of drug-susceptible
TB.
Second-line anti-TB drugs
for drug-resistant TB.
Treatment
37. Regimens Of Antituberculosis Drugs
Active disease
Treatment requires a minimum of 6 months in two phases
Intensive phase
Isoniazid,rifampin,ethambutol and pyrazinamide”given for
2 months”
Continuation phase
Isoniazid and rifampin”for 4 months
Latent disease
Daily isoniazid therapy for 9 monthes
“Monitor the patient for signs and symptoms of hepatitis and
peripheral neuropathy”
41. Resistance
Two types
Primary”intrinsic” resistance
Infection with strains naturally resistant to one or
two drugs
Hydrophobic cell wall
Drug modifying enzymes
Drug efflux system
Acquired resistance
Infection with strains that become drug resistant
d.t inappropriate or inadequate treatment
42. Drug resistance in TB
MDR (Multi-Drug Resistant)
Simultanous resistance to 2 or more drugs
from 1st
line
XDR (Extensive Drug
Resistance)
Strains not only resistant to 1st
line but also
resist fluoroquiolones and one of injectible
drugs
48. How can tuberculosis be prevented?
The BCG vaccine.
It usually protects children and infants from the
disease, but its effects wear off when the patient
reaches adulthood.
Eating a healthful diet that boosts the immune
system
Having regular TB tests if you work or live in
a high risk environment
Completing a TB medication regimen.
If you are infected, stay home, cover your mouth,
and ensure proper ventilation.
Notes de l'éditeur
There are several other species and subspecies that are included in the Mycobacterium tuberculosis complex because of their close genetic relationship to tuberculosis: [Review the slide content]
With the exception of M. pinnipedii, all of the species in the Mycobacterium tuberculosis complex have been shown to cause disease in humans; however, M. tuberculosis is by far the most prevalent
Mycobacterium tuberculosis is the organism responsible for most of the tuberculosis infection and disease seen in the Caribbean
Image Credit: CDC Public Health Image Library/Dr. George P. Kubica
Pose question to participants “How is TB transmitted?”
Solicit their responses then proceed to review slide content
Transmission is the spread of organisms, such as M. tuberculosis, from one person to another
The primary mode of transmission for tuberculosis is through inhalation of infectious particles
Less frequently, TB can be transmitted by:…[Review slide content]
*Slide Animation
Image Credit: Cartoon from clip art.; Graphic from CDC Core Curriculum. 2000.
Review the slide content
Tuberculosis disease can develop very soon after infection or many years after infection
In individuals without HIV co-infection, about 5% of people who have been recently infected with M. tuberculosis will develop TB disease in the first year or two after infection. Another 5% will develop disease later in their lives. The remaining 90% will stay infected, but free of disease for the rest of their lives
It’s important to remember that not all patients with active TB disease will have a positive Mantoux TST (approx. 75% will have +TST and this percentage is lower in HIV infected patients). Never stop evaluating a patient for active TB simply because the Mantoux TST is 00mm!
The chest X-ray will often show abnormalities suggestive of active TB but may be within normal limits for some patients with active disease, particularly if they also have HIV. This will be covered in more detail in Module 4 on Case Finding and Diagnosis
Image Source: Centers for Disease Control and Prevention (CDC)
If the immune system is compromised, then the bacilli multiply and spread to other sites in the body. People who have TB infection but not TB disease are NOT infectious - in other words, they cannot spread the infection to other people
Persons with LTBI have a low bacillary load (e.g., ≤~103)
It is very important to remember that TB infection is not considered a case of TB
Image Source: Centers for Disease Control and Prevention (CDC)
This next section describes the pathogenesis of TB (the way TB infection and disease develop in the body)
At first, the tubercle bacilli multiply in the alveoli and a small number enter the bloodstream and spread throughout the body (dissemination)
Bacilli may reach any part of the body, including areas where TB disease is more likely to develop. These areas include the upper portions of the lungs, as well as the kidneys, the brain, and bone
Disseminated TB refers to TB that simultaneously involves multiple organs. While “miliary” is given as an example of disseminated TB, it really refers to a radiographic manifestation of disseminated TB. It’s important to note that not all patients with disseminated TB have a miliary pattern on CXR
Image source: I-TECH
This slide shows different sites where TB has caused disease outside of the lungs
Image Sources:
Scrofula: http://farm1.static.flickr.com/110/283397827_f071de4335_m.jpg
Radiographic images: Francis J. Curry National Tuberculosis Center
