2. Definition of TB
Tuberculosis (TB). A chronic airborne infectious disease mainly caused by a
bacterial microorganism called mycobacterium tuberculosis or tubercle bacillus.
Transmission.
The most important source of infection is an individual with TB of the lungs.
The transmission of these tubercle bacilli occurs by airborne spread of infectious
droplets.
The infectious individual spreads the bacilli during:
• Coughing.
• Sneezing.
• Singing.
• Talking.
• Exhalation.
• Spitting
3. Causatives agents of (TB).
Tuberculosis is caused main mycobacterial species collectively
termed mycobacterium tuberculosis complex(MTB).
Mycobacterium tuberculosis.
Mycobacterium bovis.
Mycobacterium africanum.
Mycobacterium microti.
Mycobacterium canetti.
Mycobacterium caprae.
Mycobacterium Pinnipedi.
4. TYPES OF TUBERCULOSIS (TB).
There are two types of tuberculosis based on the clinical
manifestations.
Pulmonary tuberculosis (PTB).
This is the commonest that affects the lungs and is the infectious
form of the disease.
Extra-pulmonary tuberculosis (EPTB).
this is form that affects organs other than the lungs e.g. pleura,
lymph nodes,
Pericardium, spine, joints, abdomen or genital-urinary tract.
• It actually affect any part of the body.
5. There are several types of extra-pulmonary TB.
TB-lymphadenitis.
-this can result in a chronic sinus or ulcers that heals with scarring.
Pleural effusion, pericardial effusion, and tuberculosis ascites.
-Inflammatory tuberculosis effusion may occur in the pleural,
pericardial or peritoneal cavities.
Spinal TB
-tuberculosis of the spine (Pott’s disease) is a severe form of extra-
pulmonary tuberculosis.
- The TB infection starts from the inter-vertebral disc and spreads
along the anterior side to the adjacent vertebral bodies.
6. Types of Extra-pulmonary TB cont.…
• Miliary TB
-Miliary TB is blood-borne dissemination of tuberculosis from either a
primary infection or erosion of a secondary tuberculous lesion into a
blood vessel (TB bacteremia).
-Miliary TB is common in late stage of HIV and AIDS disease.
TB meningitis.
-TB of the meninges may occur from a rupture of a cerebral
tuberculoma into the subarachnoid space.
7. Risk factors for Tuberculosis (TB) infections.
Contact with high-risk groups.
- Frequent travel to high incidence areas.
Immune deficiency
– HIV infection.
– Corticosteroids or immunosuppressant therapy.
– Chemotherapeutic drugs.
– Nutritional deficiency (vitamin D).
– Diabetes mellitus.
– Chronic kidney disease.
– Malnutrition and Aging.
Lifestyle factors:
– Drug/alcohol misuse.
– Homelessness.
Genetic susceptibility (twin studies of gene polymorphisms)
8. Pathophysiology of tuberculosis TB.
Inhalation of mycobacterium tuberculosis leads to one or four possible outcomes.
• immediate clearance of the organism.
• Latent infection.
• The onset of active disease (primary disease).
• Active disease many years later (reactivation disease).
Among individuals with latent infection and no underlying medical problems ,
reactivation is markedly increased in patients with HIV [2]. These outcomes are
determined by the interplay of factors attributable to both the organism and the host.
• Primary disease.
Among the approximately 10 per cent of infected individuals who develop active disease,
about half will do so within the first two to three years and are described as developing
rapidly progressive or primary diseases.
9. Pathophysiology of tuberculosis TB Cont…
• The tubercle bacilli establish infection in the lungs after they are carried in
droplets small enough (5 to 10 macrons) to reach the alvealor spaces, if
the defense system of the host fails to eliminates the infection , the bacilli
proliferate inside alvealor macrophages produce cytokines and chemokines
that attract other phagocytc cells, including monocytes, other alveolar
macrophages and neutrophils , which eventually form a nodular
granulomatous structure called the tubercle.
• If the bacterial replication is not controlled, the tubercle enlarges and the
bacilli enter local draining lymph nodes. This leads to lymphadenopathy, a
characteristic manifestation of primary tuberculosis (TB). The lesion
produced by the expansion of the tubercle into the lung parenchyma and
lymph node involvement is called the ghon complex. Bacteremia may
accompany initial infection.
10. Pathophysiology of tuberculosis TB Cont…
• The bacilli continue to proliferate until an effective cell –mediated
immune (cmi) response develops , usually two to six weeks after
infection . Failure by the host to mount an effective CMI response and
tissue repair leads to progressive destruction of the lung . Tumour
necrosis factor TNF –alpha ,reactive oxygen and nitrogen intermedites
and the contents of cytotoxic cells ( granzymes , perforin) may all
contribute to the development of caseating necrosis that characterize
a tuberculos lesion
11. Pathophysiology of tuberculosis TB Cont…
Unchecked bacterial growth may lead to haematogenous spread of
bacilli to produce disseminated TB . Disseminated disease with lesions
resembling millet seeds is termed Miliary TB . Bacilli can also spread by
erosion of the caseating lesions into the lung airways –and the host
becomes infectious to others. I the absence of treatment ,death ensues
in 80 per cent of cases (3). The remaining patients develop chronic
disease or recover. Chronic disease is characterized by repeat episodes
of healing by fibrotic changes around the lesions and tissue breakdown
. Complete spontaneous eradication of bacilli is rare .
12. REACTIVATION DISEASE
• reactivation TB occurs from proliferation of a previously dormant
bacterium seeded at the time of primary infection . Among individuals with
latent infection and no underlying medical problems ,reactivation disease
occur in 5 to 10 percent(1) . Immunosuppression is associated with
reactivation TB ,although it is not clear what specific host factors maintain
the infection in a latent state and what triggers the latent infection to
become overt . See previous article (4) for immunosuppressive conditions
associated with reactivation TB . The disease process in reaction TB tends
to be localized [ in contrast to primary disease ] there is little regional
lymph node involvement and less caseation . The lesion typically occurs at
the lung apices , and disseminated disease is unusual unless the host is
severely immunosuppressed . It is generally believed that successfully
contained latent TB confers protection against subsequent TB exposure
13.
14. Clinical features.
The most common symptoms of pulmonary tuberculosis are:
• Persistent cough for 2 weeks or more; every patient presenting with this symptom should be
regarded as a suspect
• Sputum production, sometimes bloodstained.
• Shortness of breath.
• Chest pain.
• Fatigue (tiredness).
• General malaise.
• Loss of appetite.
• Loss of weight .
• Night sweats.
• Fever.
15. The symptoms for extra-pulmonary
tuberculosis (TB).
It depend on the organs involved, for example:
• Chest pain from pleurisy.
• Swelling of lymph nodes in tuberculosis lymphadenitis.
• Pain and swelling of joints in tuberculosis arthritis.
• Deformity of the spine with or without neurological deficit in TB of
the spine.
• Headache, fever, stiffness of the neck and mental confusion in
tuberculous meningitis (TBM).
17. INVESTIGATIONS.
Sputum- smears microscopy or sputum for rapid
molecular tests like Gene –Expert to rule out
acid fast bacilli.
Culture and sensitivity; this is done for
diagnosis of drug resistance and surveillance.
Chest X-rays: done to assist clinical diagnosis of
TB or in case of triaging presumptive.
19. TREATMENT
Pharmacological Treatment TB treatment.
-is divided into two phases:
Initial /intensive phase, which consists of:
• RHZE for 2 months - new and re-treatment cases
Continuation phase, which consists of:
• RH for 4 months - new and re-treatment cases
• RH for 10 months for severe forms TB such TB meningitis,
Miliary TB and TB of the spine.
20. Recommended daily dose - regimens of first-line anti-TB drugs for adults
and children
New/retreatments Initial phase Continuation phase
New/retreatments Rifampicin + isoniazid +
pyrazinamide and
ethambutol in fixed dose
(RHZE) for 2 months
Rifampicin + isoniazid in
fixed dose (RH) for 4
months
Daily dosage of anti-TB drugs (FDCs) in new and retreatment
and patients
Body weight Number of tablets in initial
phase: 2 months
(R150/H75/Z400/E275) mg
Number of tablets in continuation
phase: 4 months (R150/H75) mg
21-30 kg 2 2
31-50 kg 3 3
51-74 kg 4 4
≥75 kg 5 5
