Pulmonary Tuberculosis
Pulmonary Tuberculosis
Includes Diseases: Multi-drug-resistant tuberculosis...
Etiology
Risk Factors
- Close contact with sputum smear positive individual
- Environmental factors : that lower resistance- Malnutrition, poor and over crowded housing, alcoholism and /or drug addiction, heavy smoking, corticosteroid therapy.
- Relation to other disease : Not uncommon after influenza, whooping cough. More common with diabetes mellitus, cirrhosis of liver, pneumoconiosis and partial gastrectomy.
- Immunosuppression : including drugs and (autoimmune deficiency syndrome)
- HIV infection/AIDS
- Other risk factors : Renal failure, diabetes, silicosis, family history, IV drug abuser.
Route of infection :
In majority by inhalation of air born infected droplet nuclei derived from sputum of an adult with cavity pulmonary tuberculosis.
Clinical types :
1 . PRIMARY PULMONARY TUBERCULOSIS
I . Primary Pulmonary Tuberculosis
Primary tuberculosis referred to events following invasion by tubercule bacillus infection, being commonly caused by inhalation (rarely through skin or ingestion) of the bacilli into the lungs.
Primary complex
Inhaled bacilli are deposited in the alveoli where a subpleural inflammatory leision occurs. When they reach the regional lymph nodes, these also become positive within 6 weeks of the infection. These two components of the primary complex may resolve without complications and sometimes results in local calcification.
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| Primary Tuberculosis / Paratracheal and Hilar Lymphadenopathy |
PROGRESS - of primary complex may occur thus -
1 . Hematogenous dissemination
About 3 months after primary infection.
a . Acute type : Miliary tuberculosis,, TB meningitis.
b . Chronic type : with local manifestations in kidneys, bones, joints etc.
2 . Progress of lung component
Most commonly in adolescents and young adults usually about 6 months after initial infection. The lung focus extends and cavitates and pleural involvements leads to pleural effusion.
3 . Progress of lymph node component
It may cause pressure on traches or main bronchi resulting in severe paroxysmal cough stimulating whooping cough. There may also be dyspnoea, strider or wheezing which may be mistaken for asthma.
4 . Bronchial involvement
a . Partial bronchial obstruction with valve action causing obstructive emphysema or
b Complete bronchial obstruction may result in large areas of homogenous shadowing (formerly labelled epituberculosis). Bronchial involvement commonly involves middle lobes and upper lobes. Aspiration of infected material causes pneumonias or collapse. Lesions may clear without sequelae but sometimes result in permanant collapse, broncho stenosis, bronchiectasis or obstructive emphysema.. The large middle lobe bronchus is particularly vulnerable and the bronchiectasis may lead to recurrent middle lobe infection(middle lobe syndrome).
Reinfection
1 . Absence of enlarged hilar lymph nodes.
2 . Usually subapical location.
3 . Tendency to cavitation and progress.
4. Spread bronchogenic hence disease is localized to the lungs,
5 . Healing of leision by fibrosis.
Primary complex
1 . Enlargement of hilar lymph nodes.
2 . Any part of lung.
3 . Usually heals, Cavitation rare, thin walled.
4 . Spread by lymphatic route and homogenous. Miliary spread common
5 . Healing of leision mainly by calcification.
Management
Rifampicin 12 mg/kg body weight (maximum 600mg) and INH 5 mg/kg body weight in two divided doses. Streptomycin 50mg/kg/day can be added in a severe case. If lesion is not resolving bronchoscopy should be done and the bronchus sucked out as collapse may be associated with retained secretions.
II Post Primary tuberculosis - may occur
(1) As a progressive primary leision.
(2) As a result of reactivation of primary leision.
(3) Due to subsequent exogenous infection.
A . Acute Pulmonary tuberculosis
1 . PNEUMONICTUBERCULOSIS
Affects usually the upper lobes, rarely whole lung. Symptoms like acute lobar pneumonia, bur irregular temperature, rapid breathing, sweats, signs of cavitation. Leucopenia and failure to respond to antibiotics.
2 . BRONCHOPNEMONIC TUBERCULOSIS.
Abrupt onset of times following influenza or in children measles or whooping cough or as a sequel of hemoptysis with aspiration of tuberculous matter into bronchi. Signs of diffuse bronchitis in early stage, later areas of consolidation especially at apex. Rapid wasting. X-ray shows a scattered foci, throughout lungs. May be rapidly fatal.
3 . MILIARY TUBERCULOSIS
Clinical features-
(a) Onset- Gradual with vague health, loss of weight and fever.
(b) Fever - Irregular, wide variation between morning and evening
(c) Hepatomegaly- In 20-30% of cases.
(d) Respiratory symptoms- Dyspnoea and cyanosis out of proportion to signs in chest. Slight dry cough, scattered rhonchi and occasional creps.
(e) Nervous symptoms-Headache common, often severe, signs of meningeal irritation in early stages.
(f) Cardio-Vascular Symptoms - Tachycardia.
(g) Skin- Miliary leisions of skin rarely present as macules, papules or purpuric lesions.
(h) Fundus - Choroidal tubercles pathognomonic. Seen as single or multiple yellowish white spots which later become pigmented.
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| Miliary tuberculosis/ miliary mottling |
X-ray Scattered opacities throughout the lung fields "Snow storm appearance."
Complications -
1 . TB meningitis
2 . Pleural effusion or polyserositis
3 . Cervical lymphadenitis
4 . Hypokalemia.
5 . Blood dyscrasias- anemia with pancytopenia, at times leukemoid reaction purpura.
4 . ACUTE DISSEMINATE HEMATOGENOUS TUBERCULOSIS
(a) Clinical feature
- Pyrexia of unknown origin lasting over few weeks with sudden detoriation especially in immunocompromised patients.
- Sputum absent or scanty
- ARDS
- Tachypnoea
- Development of dysfunction of multiple organs resembling sepsis
- CXR - Miliary or scattered shadows
- Bronchoscopy-AFB may be cultured from samples from the bronchoalveolar lavage (BAL) and caseating granulomas may be seen on histopathology of leision obtained from transbronchial biopsy
- Liver cell dysfunction.
B. Chronic pulmonary tuberculosis
Drug resistance tuberculosis
MODES OF PRESENTATION
1 . Symptom free- Diagnosis on routine radiography'
2 . Insidious - Malaise, undue fatigue, loss of weight, evening rise of temperature and cough.
3 . Persistent cough or "smoker's cough"
4 . Unexplained loss of weight.
5 . Pyrexia of unknown origin-
6 . Catarrhal or Influenzal- Repeated attacks of colds and run down feeling, or failure to recover adequately from attack of influenza.
7 . Hemoptysis-Sudden large hemoptysis due to erosion of an artery in a cavity or more often recurrent hemoptysis of small quantity.
8 . Non resolving pneumonia.
9 . Hoarseness of voice- due to laryngeal tuberculosis that occasionally complicates severe pulmonary infection.
10 , Pleural - (a) Pleurisy dry or with effusion (b) Spontaneous pneumothorax.
11 . Traumatic- Following injury to chest or "gassing"
12 . Following certain disease= such as measles, whooping cough especially if complicated by broncho pneumonia.
13 . Senile - Slow onset, symptom of bronchitis or emphysema.
14 . Asthmatic- Usually young patient start getting attacks of so called "bronchial asthma" for the first time.
15 . Amenorrhea or oligomenorrhoea-may be the presenting symptom in young women.
16. Lymph node enlargement- including hilar, mediastinal and cervical groups or generalized with spleenomegaly.
17. Mental symptoms-such as irritablity and difficulty in concentration suggesting neurosis.
18 . Patients who have had previous gastrectomy for peptic ulcer.
19 . Initial presentation of AIDS in HIV positive patients (Most TB in such cases is reactivation of past infection).
Symptoms
1 . Local Pulmonary symptoms-
a . Cough- early symptom. Mostly at night and in early morning. In early stages often dry and hacking, later loose with sputum. With cavitation often paroxysmal especially in morning. Localized wheezing may be complained of due to bronchial narrowing by tuberculous lymph nodes
b . Sputum- may be absent in early stages. Not characteristic until late stage when nummular
c . Haemostasias -In early stage blood stained sputum, later from cavity may be profuse
d . Dyspnoea -usually manifestation. of extensive disease, pneumothorax or rapid development of large pleural effusion.
2 . General (constitutional ) symptoms-
a . Fever- varies with extend and activity of disease and amount of exercise.
b . Sweating especially at night
c . Loss of weight
d . Anorexia
e . Lassitude
f . Palpitation due to tachycardia.
3 . Extra Pulmonary symptoms-
May result from secondary tuberculous involvement of various parts of body-meninges, larynx, pericardium, peritoneum, bones and joints, genito -urinary system.
Physical Signs-
Depends on stage and extent of disease. In initial stages signs are usually none, diagnosis being radiological.
1 . Early signs- are post tussive crepitations heard most commonly at the lung apices and localized wheeze may be audible in relation to narrowed bronchi.
2 . Signs of consolidation- Limitation of movements over affected parts of chest. diminish pulmonary resonance, bronchial breath sounds.
3 . Signs of cavitation- Impaired note or tympanic note if cavity large. Breath sounds bronchial, cavernous or amphoric depending on size of cavity. Cracking rales.
4 . Signs of fibrosis :Affected side of chest flattened with displacement of apex impulse to side of leision. Vocal resonance increased if lung considered and large bronchi patent, diminished if much pleural thickening. Clubbing of fingers sometimes.
Diagnosis
1 . Sputum-Repeated examination neccessary. If sputum not available. laryngeal swabs, morning gargle lavage or specimens obtained by tracheo- bronchial suction are appropriate.
2 . Chest Radiograph- features are
- Presence of opacities mainly in the upper zone, with a patchy or nodular appearance.
- Cavitation.
- Calcification.
- Dense nodular rounded or oval leisions (tuberculoma ot bronchial cold abscess)
3 . ESR- Usually increased.
4 . Tuberculin Test-
a . Mantoux test
0.1 ml of freshly prepared purified protein derivative (PPD) 100units per ml is most commonly used. The diameters of the reaction is read in millimeters at 72 hours. An induration of 10mm or more is regarded as positive. If BCG have not been and and induration is 15 mm as positive if BCG has given
(b) Heaf test
Six multi punctures are made in the skin through a drop of undiluted PPD,100,000 IU/ML containing 2 mg/ml of tuberculin. The test site is read between 2 and 7 days. Positive reactions are divided into 4 grades-
1 . 4-6 papules.
2 . Ring of induration.
3 . Disk of induration.
4 . Disk of induration100 mm. and /or vesiculation. Grade of 2-4 is regarded as positive in absence of previous BCG and grade 3-4 if BCG is previously.
Factors which may depress the skin reaction in a positive reactor are-
1 . Old age
2 . Healed childhood tuberculosis. Intercurrent severe illness with high fever.
4 . For some weeks after measles and infectious mononucleosis.
5 . Sarcoidosis.
6 . Miliary tuberculosis or overwhelming tuberculosis any where in the body.
7 . Administration of corticosteroids.
8 . Malignant lymphomas.
9 . Recent infections so that hypersensitivity has not developed.
10 . Inactive old tuberculin.
11 . Immunosuppression.
5 . Other diagnostic techniques-
(a) Serological : Antigen detection by ELISA, competitive inhibition of the binding of monoclonal antibodies. Immunoblotting techniques and agglutination based tests. Antibodies have been detected in CSF, pleural fluid and bronchial washings
(b) Polymerase chain reaction (PCR) : For M. tuberculosis the IS6110 DNA sequence is most commonly used.
(C) Restriction fragment link polymorphism : variants of DNA restrictions sites have been identified among M. tuberculosis isolated by endonuclease restriction and electrophoresis.
Complications-
Early
Pneumonia
Empyema
Hemoptysis
Laryngitis
Pneumothorax
Late
Bronchiectasis
Mycetoma's in cavities
Colonization of fibrotic lung with non-tuberculous mycobacterium
Non -respiratory disease (e.g. genitourinary, bone)
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| Large chronic Tuberculous cavity at right apex |
Management
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| Pleural thickening |
Diagnosis
1 . Clinical
- No visible clinical improvement inspite of regular and adequate chemotherapy for 1-3 months.
- Presence of multiple or giant cavities
- Serial X-ray showing detoriation or no improvement after 3 months of therapy
- "fall and rise" phenomenon in which direct sputum smear examination initially shows a fall in number of bacteria followed by a gradual rise in count due to rise of resistant organism.
2 . Laboratory
- Sputum is positive by direct smear even after 5 months of adequate therapy
- Culture and sensitivity test of bacilli by slide culture, use of egg enriched sheep blood media (EESBM). Bactac system of radiometric detection of mycobacterial growth. Luciferace reporter Myco-bacteriophage test (LRM test)
Management
1 . Rest
Indications-Pyrexia, hemoptysis, drug reaction, relapse.
2 . Chemotherapy
Combination drug therapy is obligatory.
All drugs except PAS should be give in a single dose.
Rifampicin should be given11/2 hour later before breakfast.
Rifampicin , Isoniazid can be given in a combined preparation.
Treatment Regimens
Short term chemotherapy
Is based on selection of drug combinations which sterilize rapidly. Two drug action are involved-
(a) Killing of dividing bacilli(Isoniazid and Rifampicin)
(b) Killing of "persisters " (Rifampicin and Pyrazinamide.
2HRZ/4HR regimen
Initial phase (2 months)
Isoniazid
Rifampicin
Pyrazinamide
If drug resistance expected:
Add Ethambutol or Streptomycin
If pyrazinamide is not tolerated:
Ethambutol (continuation phase 7 months)
Continuation phase (4 months)
Isoniazid
Rifampicin
Drug resistance tuberculosis
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