T.B. in human, diagnosis and treatment.

1. M. tuberculosis

2. - Reservoir: Humans
- Transmission: Airborne disease (aerosol transmission)
- Symptoms:
Latent TB infection: Active TB infection:
No symptoms Bad cough
*Cannot spread TB Coughing up blood/sputum (Hemoptysis)
(Dormant infection) Chest pain
Loss of appetite
Weight loss
Fever
Chills
Night sweats
Swollen glands
*Contagious
Extra-pulmonary TB: Symptoms depend on location of infection
General symptoms: fatigue, fever, loss of appetite and weight loss.
TB of lymph nodes: swelling of lymph nodes
TB meningitis: neurological symptoms including headache
Spinal TB: Mobility impairments, pain

3. Chest X-ray of a person with advanced tuberculosis. Infection in both lungs
is marked by white arrow-heads (Caseous necrosis), and the formation of a
cavity is marked by black arrows.

4. General Characteristics
- Family – Myobacteria
- Aerobic rod-shaped bacilli
- “Acid fast” bacteria
- Lack of spore formation and toxin production
- No capsule, flagellum (non-motile)
- Generation time of 18- 24 hours but requires 3-4
weeks for visual colonies
Pathological Features
- Principle cause of Human Tuberculosis
- Intracellular pathogen (alveolar macrophages)
- Waxy, thick, complex cellular envelope
- Produces tubercles, localized lesions of M.
tuberculosis
SEM of M. tuberculosis
M. Tuberculosis
(stained in purple)

5. General Features
- Thick, waxy and complex
- Higher fluidity in more external regions
than internal regions
- Relatively impermeable to hydrophilic
solutes
- Contain porins protein (selective
cationic + channels)
Main Components
- Peptidoglycan
 contains N-glycolylmuramic acid
instead of N-acetylmuramic acid
- Arabinogalactan
(arabinose+galactose)
- Mycolic Acids (60% of cellular
envelope)
- Lipoarabinomannan (LAM) glycolipid
(virulence factor)

6. Specimen:
• Sputum, chest x-ray and surgical biopsy.
• CSF- if tubercuosis meningitis is suspected
Microscopy:
• Acid fast rods
• Non-motile
• Non sporing
• Obligate aerobe
• Non capsulated
• Ziehl-neelson staining is used
Culture:
Grow slowly with doubling time of 18 hours. (the amount of time it
takes for a cell to divide) (such as a tumor) to double in size.
Lowenstenin Jensen agar
Raised, dry, cream colored colonies are visible after 2 to 3 weeks and sample
is not discarded until 6 weeks of incubation.
Nucleic acid amplification test (PCR)

7. Diagnosis of TB ?

11. 1) Diagnose tuberculosis rapidly by identifying DNA from M.
tuberculosis in clinical samples.
2) Determine rapidly whether acid-fast organisms identified by
microscopic examination in clinical specimens are
M.tuberculosis
3) Identify the presence of genetic modifications known to be
associated with resistance to some anti mycobacterial
agents.
4) Determine whether or not isolates of M.tuberculosis from
different patients have a common origin in the context of
epidemiological studies.

12. 4- Direct Microscopy identification
M. tuberculosis is a acid–fast
bacterium, rod-shaped bacterium
measuring 2-4 x 0.2-0.5 μm. They
appear as bright red rods against a
contrasting background.
The Ziehl-Neelsen stain is used to
demonstrate the presence of the bacilli
in a smear. The technique is simple,
inexpensive and detects those cases of
tuberculosis who are infectious.

13. Antibacterial chemotherapy:
- Combination of first and second line drugs for the first
2 months which could include:
- Isoniazid
- Rifampicin
- Pyrazinamide
- Streptomycin or Ethambutol
- Next 4 months, combination of:
- Isoniazid
- Rifampicin
Early resistance to isoniazid: other first-line drugs
such as ethambutol, streptomycin, pyrazinamide and
fluoroquinolones can be added to drug arsenal (treatment
period also extended).
- These drugs are relatively effective in killing the bacteria,
however, they also produce a wide variety of side effects.

14. First line drugs:
- Bactericidal agents: kill (destroy) active bacteria, important in
the early stages of infection.
Second line drugs:
- Bacteriostatic: hinder (inhibit) bacterial growth.
- Strengthen treatment in the case of resistant bacteria.
- Less efficient and generally more toxic than first line drugs.
Inappropriate chemotherapy:
- Monotherapy (single drug treatment)
- Decreased treatment period
- Low absorption of drugs

15. Drug Bactericidal or
Bacteriostatic
Mechanism of Action Mutation
Rate
Side Effects
Isoniazid Bactericidal to
rapidly dividing
bacteria and
bacteriostatic to
slowly dividing
bacteria
Pro-drug: activated by a
bacterial catalase.
Inhibits enoyl-ACP reductase
(key enzyme in fatty acid
synthesis, different than
equivalent mammalian
enzymes)
1 in 105 - 106 Rash, abnormal liver function,
anemia, peripheral neuropathy,
mild CNS effects
Rifampicin Bactericidal Inhibits transcription by RNA
polymerase
1 in 108 Fever, immune reactions, GI
irritation, liver damage, can
cause tears and urine to turn
red/orange
Streptomycin Bactericidal Inhibits initiation of protein
synthesis
1 in 108 - 109 Damage to the ears, nausea,
rash, vomiting, vertigo
Ethambutol Bacteriostatic Prevents formation of the cell
wall
1 in 107 Decrease in visual acuity,
colourblindness and other visual
defects, joint pain, nausea,
vomiting, fever, malaise,
headache, dizziness
Fluoroquinolones Bactericidal Act manly on DNA gyrase
(DNA gyrase: introduces
negative supercoils into DNA)
Tendon damage, heart problems,
swelling of face and throat,
shortness of breath, rash, loss of
consciouness
Pyrazinamide Bacteriostatic,
Bactericidal
Accumuates causing cellular
damage
Joint pain, nauseau, vomiting,
rash, malaise, fever,
photosentivity

16.  Bacille Calmette-Guerin (BCG) Vaccine is
available, and is used for tuberculin-
negative individuals under sustained
heavy risk of infection.
 Isoniazid is used prophylactically, e.g.
for tuberculin positive, asymptomatic
individuals, who need
immunosuppressive therapy
for other illnesses

17. THANK YOU