DUHS CME - Ojha Institute of Chest Diseases





Diagnosis of TB


In this module we will learn about


Tuberculosis should be defined accurately for registration and programmatic management.

Tuberculosis Suspect

Any person who presents with symptoms or signs suggestive of Tuberculosis.

The most common symptom of pulmonary TB is

  • A productive cough for more than 2 weeks, Which may be accompanied by Other respiratory symptoms.
  • shortness of breath,
  • chest pains,
  • haemoptysis and/or Constitutional symptoms,
  • loss of appetite,
  • weight loss,
  • fever, night sweats,
  • fatigue.

The suspicion of tuberculosis is much more likely to be correct in patients with the above-mentioned symptoms and history of close contact with a smear-positive tuberculosis patient.
For extra-pulmonary tuberculosis, symptoms depend on the organ involved. Tuberculosis should be suspected in the differential diagnosis of any patients with the following symptoms for example:

  • Cough and shortness of breath with pleural or pericardial effusions.
  • Swelling, occasionally with pus discharge when lymph nodes are affected.
  • Joints pain and swelling.
  • Headache, fever, neck stiffness and confusion in possible tuberculosis meningitis.
  • Backache with or without loss of function in lower limbs when there is Gibbous and spinal involvement.
  • Abdominal pain, diarrhea or ascites with abdominal involvement.
  • Infertility when genital organs are affected.

Case of tuberculosis.
A definite case of TB (defined below) or one in which a health worker (clinician or other medical practitioner) has diagnosed TB and has decided to treat the patient with a full course of anti-TB treatment.
Note. Any person given treatment for TB should be recorded as a case. Incomplete “trial” TB treatment should not be given as a method for diagnosis.

Definite case of tuberculosis.
A patient with Mycobacterium tuberculosis complex identified from a clinical specimen, either by:

  • Culture
  • A newer method such as molecular line probe assay and GeneXpert.
  • Initial sputum smear examinations positive for acid-fast bacilli (AFB).
(In settings that lack the laboratory capacity to routinely identify M. tuberculosis)).

Cases of TB are also classified according to the:

  • Anatomical site of disease.
  • Bacteriological results (including drug resistance).
  • History of previous treatment.
  • HIV status of the patient.

Diagnosis of Tuberculosis

Case-finding methods:
The highest priority of TB control is the identification and treatment of infectious cases, i.e. persons with smear-positive pulmonary TB.

Most TB cases are diagnosed through:
1. Passive case finding: Persons presenting with symptoms
2. Active case finding: The screening of high-risk populations using mass miniature radiography (MMR*), standard chest radiography, sputum smear microscopy

The following recommendations offer some of the best prospects for significant yield of cases.

  • Patients who present themselves at health facilities with cough for 2 weeks &/OR with relevant symptoms should be considered a TB suspect and should be examined.
  • household contacts (especially children and young adults) of all smear-positive tuberculosis patients should be examined.
  • Patients for any reason, who found to have some radiological changes should be subjected to the bacteriological examination.

Identifying Pulmonary Tuberculosis amongst Patients with Cough
A patient with persistent cough for more than 2 weeks is a pulmonary TB suspect and must submit sputum for diagnostic microscopy
Most patients with pulmonary TB develop a persistent cough soon after disease onset. However, cough is not specific to pulmonary TB. Therefore, other causes should be excluded. For example Cough is common in smokers and in patients with acute upper or lower respiratory tract infection.

Criteria for a TB Suspect
National TB Control program uses following criteria for diagnosis of TB patients.

  • A patient with persistent cough for 2 weeks or more
  • Patients with a cough of less than 2 weeks, or of uncertain duration, are also TB suspects if they also have one or more of the following:
  • Blood stained sputum.
  • Fever usually at night.
  • Weight loss.
  • History of previous TB.
  • History of close contact of TB patient.

The Bacteriologic Examination
Clinical specimens (for example, sputum or urine etc) are examined and cultured in the laboratory for the bacteriologic examination.

The bacteriologic examination has five parts:

  • Specimen collection.
  • Examination of the acid-fast bacilli smears.
  • Direct identification of specimen (nucleic acid amplification).
  • Specimen culturing and identification.
  • Drug susceptibility testing.

Specimen Collection
Specimens that will be sent to the laboratory can be obtained in several ways. Usually, patients who are suspected of having pulmonary TB disease simply cough up sputum (phlegm from deep in the lungs) into a sterile container for processing and examination.

This is the least expensive and easiest procedure. A health care worker should coach and directly supervise the patient when sputum is collected.

Patients who are not supervised are not always successful in providing an adequate specimen, especially in their first attempt.




Methods of Obtaining a Sputum Specimen





Coughing up sputum

Patient coughs up sputum


Easy to do

Patient may not be able to cough up sputum on his or her own, or may spit up saliva instead of sputum

Inducing sputum

Patient inhales a saline mist, causing him or her to cough deeply

Easy to do

Specimens may be watery and may be confused with saliva (should be labeled “induced specimen”) Requires special equipment


Bronchoscope is passed through the mouth or nose directly into the diseased portion of the lung, and some sputum or lung tissue is removed

Useful for obtaining sputum when coughing or inducing sputum does not work

Most expensive and invasive procedure Requires special equipment Must be done by a specialized physician in a hospital or clinic

Gastric washing

Tube is inserted through the patient’s nose and passed into the stomach to get a sample of gastric secretions that contain sputum that has been coughed into the throat and then swallowed

Useful for obtaining samples in children, who usually produce little or no sputum when they cough

Must be done as soon as patient wakes up in the morning; patient may be required to stay in hospital Can be uncomfortable for the patient


a) Sputum Examination
Sputum examination is the most specific, cost effective and reliable test for diagnosis of pulmonary TB.

Three specimens of sputum must always be collected for a TB suspect.

This is because some cases of TB will be missed if less than 3 sputum samples are examined.

Sputum samples should be collected as follows:

1. Spot 1: This is collected on first consultation.

2. Early morning: This is collected at home and this is the early morning sputum sample collected the day after consultation.

3. Spot 2: This is collected at the lab on the same day when the morning specimen is submitted.

Quality of Sputum
Steps for taking good sputum samples are as follow:

  • Good quality specimens contain sputum, not saliva. It is important to collect a good sputum specimen in order to make sure that any bacteria present are identified.
  • A good quality specimen is obtained by explaining and demonstrating to the patient how to take in a deep breath and cough deeply in order to bring up sputum.


b) Examination of the acid-fast bacilli smears

Smear examination is done by

  • Zeil Nelsen method
  • Flourecent method


Reading Sputum Smear Results:
Sputum smear results are reported on by the laboratory staff. The doctor at the clinic/hospital will see the report to decide further action according to these results.

Specimen 1, 2 and 3 refers to three specimens collected for the laboratory examination of TB suspects.

The results column refers to result of each sputum smear examined. The smear results are reported either as positive or negative. In this column, “POS” is written to record a positive result, and “NEG” is written to record a negative result.

Positive grading refers to grading according to number of acid fast bacilli (AFB) on the slide. The laboratory person will tick the appropriate positive grading column for each smear reported “POS”.

The positive grading is done according to WHO criteria given in the table below:

If the slide has:

Results                                 Positive/Negative       (grading)             Remarks (Bacterialload)

More than 10 AFB per field               POS                            3+                                  Heavy

1 to 10 AFB per field                        POS                            2+                                 Medium

10 to 99 AFB per 100 fields             POS                             1+                                  Low

1 to 9 AFB per 100 fields                 POS             Record exact number                   Very Low

No AFB per 100 fields                      NEG             Nil/Not seen



c) Direct identification of the specimen
(nucleic acid amplification)
Nucleic acid amplification (NAA) tests can be used for directly identifying M. tuberculosis from sputum specimens. NAA tests, including polymerase chain reaction (PCR) and other methods, are used to amplify (copy) DNA and RNA segments, in to order to rapidly identify the microorganisms in the specimen.

A patient can be presumed to have TB if they have a positive NAA test with an AFB positive smear. If a patient has a negative NAA test with an AFB positive smear, the patient may have a nontuberculous mycobacteria  infection. NAA test results can help guide clinicians decisions for patient therapy and isolation; however, they do not replace the need for AFB smear, culture, or clinical judgment.

Decisions about when and how to use NAA tests for TB diagnosis should be based on each individual situation. Laboratories should not reserve specimens for NAA tests if it will compromise the ability to perform the other diagnostic tests.


d) Culturing and identifying the specimen
Culturing the specimen means growing the mycobacteria on solid media and in liquid media, substances that contain nutrients, in the laboratory (Figure 3.9). When the mycobacteria have formed colonies (groups), or when there is sufficient growth in the liquid media, they can be identified. All specimens should be cultured, regardless of whether the smear is positive or negative.

Culturing the specimen is necessary to determine if it contains M. tuberculosis and to confirm a diagnosis of TB disease.

However, in some cases, patients are diagnosed with TB disease on the basis of their clinical presentation (i.e., signs and symptoms), even if their specimen does not contain M. tuberculosis.


Colonies of M. tuberculosis growing on media.

The first procedure in culturing the specimen is to detect the growth of the mycobacteria. Mycobacteria grow very slowly. When solid media are used to culture the specimen, it can take as long as 3 to 6 weeks for the growth of the mycobacteria to be detected.

However, rapid culturing methods that involve liquid media can decrease this time to 4 to 14 days.

The second procedure is to identify the organism that has grown in the culture. All types of mycobacteria will grow in solid or liquid media.

 For this reason, laboratory tests must be done to determine whether the organism is M. tuberculosis or one of the nontuberculous mycobacteria.

 Nucleic acid probes can rapidly identify the type of mycobacteria present in the specimens in 2 to 4 hours.

 Thus, using liquid media and nucleic acid probes, it is usually possible to culture and to identify M .tuberculosis within two weeks.

If traditional solid medium and biochemical tests are used for both the isolation and identification of the organism, the entire process can take 6 to 12 weeks.

When M. tuberculosis is identified in a patient’s culture, the patient is said to have a positive culture for  M. tuberculosis.

A positive culture for M. tuberculosis, also called a M. tuberculosis isolate, confirms the diagnosis of TB disease.

When M. tuberculosis is NOT identified in a patient’s culture, the patient is said to have a negative culture for M. tuberculosis.

A negative culture does not necessarily rule out the diagnosis of TB disease.

Some patients with negative cultures are diagnosed with TB disease on the basis of their clinical presentation (i.e., signs and symptoms).

Follow-up bacteriological examinations are important for assessing the patients infectiousness and response to treatment. Specimens should be obtained monthly until 2 consecutive specimen cultures are negative.

Culture conversion is the most important objective measure of response to treatment.

Differences Between Sputum Smears and Cultures




Equipment needed

Microscope, glass slides, special dyes

Incubators, safety cabinet, culture plates or tubes, culture media, biochemicals for tests

Time needed to make report

1 day

4 days to 12 weeks (depending on method used)

Basis of procedure

Looking for AFB on slide under microscope

Growth and identification of tubercle bacilli or other mycobacteria on culture media in incubator

Significance of a negative report

Patient is less likely to be infectious Does not rule out TB disease (culture may be positive)

No live tubercle bacilli found in the specimen Does not rule out TB disease (live tubercle bacilli may be in other specimens and/or in the patient)

Significance of a positive report

Patient is more likely to be infectious (if AFB are tubercle bacilli) AFB could be nontuberculous mycobacteria

Confirms diagnosis of TB disease

e) Drug susceptibility testing
For all patients, drug susceptibility tests should be done when the patient is first found to have a positive culture for  M. tuberculosis (that is, the first isolate of M. tuberculosis).
 Drug susceptibility tests are done to determine which drugs will kill the tubercle bacilli that are causing disease in a particular patient.
Tubercle bacilli that are killed by a particular drug are said to be susceptible to that drug, whereas those that can grow even in the presence of a particular drug are said to be resistant to that drug.

The drug susceptibility pattern of a strain of tubercle bacilli is the list of drugs to which the strain is susceptible and to which it is resistant.

Drug-resistant TB can be


If the tubercule bacilli are resistant to any one TB treatment drug, Poly-resistant
If resistant to at least two TB drugs (but not both isoniazid and rifampin).

Multidrug-resistant TB (MDR TB)
If the tubercle bacilli are resistant to at least isoniazid and rifampin, the two best first-line TB treatment drugs.

Extensively drug-resistant TB (XDR TB) if the tubercle bacilli are resistant to isoniazid and rifampin, plus resistant to any fluoroquinolone and at least one of three injectable second-line drugs (such as amikacin, kanamycin, or capreomycin).

The results of drug susceptibility tests can help clinicians choose the appropriate drugs for treating each patient. This is very important. Patients with TB disease who are treated with drugs to which their strain of TB is resistant may not be cured. In fact, their strain of TB may become resistant to additional drugs.

Drug susceptibility tests should be repeated if a patient has a positive culture for M. tuberculosis after 3 months of treatment or if a patient does not seem to be getting better. That way, the clinician can find out whether the patient’s strain of TB has become resistant to certain drugs; if necessary, the clinician may change the drugs used for treating the patient. Clinicians treating patients with drug-resistant TB should always consult with a medical expert who is familiar with the treatment of drug-resistant TB.

In the laboratory, drug susceptibility testing can be done using a liquid medium or a solid medium method. In a drug susceptibility test, organisms that grow in media containing a specific drug are considered resistant to that drug .

Liquid medium methods are faster than solid media methods for determining susceptibility to first-line TB medications. Usually the susceptibility results can be obtained within 7 to 14 days with the liquid medium method. Traditional solid medium methods, can take as long as 21 days.


Latent TB Infection (LTBI)

Latent TB infection (LTBI) means that tubercle bacilli are in the body, but the body's immune system is keeping the bacilli under control and inactive. The immune system does this by producing special immune cells that surround the tubercle bacilli. The cells form a shell that acts as a fence and keeps the bacilli contained and inactive.

LTBI is detected by the Mantoux tuberculin skin test (TST) or an interferon-gamma release assay (IGRA) such as the QuantiFERON®-TB Gold test (QFT-G). Most people with LTBI have a positive TST or QFT-G result. Module 3, Targeted Testing and the Diagnosis of Latent Tuberculosis Infection and Tuberculosis Disease, discusses the TST and the QFT-G in more detail.

People who have LTBI but not TB disease are NOT infectious — in other words, they cannot spread the infection to other people. These people usually have a normal chest x-ray. It is important to remember that LTBI is not considered a case of TB. Major similarities and differences between LTBI and TB disease are shown in the Table below.

LTBI vs. TB Disease

Latent TB Infection (LTBI)
TB Disease (in the lungs)
Inactive tubercle bacilli in the body Active tubercle bacilli in the body
Tuberculin skin test or QuantiFERON®-TB Gold test results usually positive Tuberculin skin test or QuantiFERON®-TB Gold 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


The Mantoux Tuberculin Skin Test (TST)

The TST is used to determine if a person is infected with  M. tuberculosis.
In this test, a substance called tuberculin is injected into the skin.
Tuberculin contains antigens used for diagnosing TB infection; it is not a vaccine.
An antigen is a protein substance that can produce an immune response. Tuberculin is made from proteins derived from tubercle bacilli that have been killed by heating.
In most people who have TB infection, the immune system will recognize the tuberculin because it is similar to the tubercle bacilli that caused infection.
This will cause a reaction to the tuberculin at the site of the injection.
Tuberculin used for the skin test is also known as purified protein derivative, or PPD.
For this reason, the TST is sometimes called a PPD skin test.



Positive PPD skin test


Interpreting the TST Reaction

TST Reaction 5 or more millimeters

10 or more millimeters

15 or more millimeters

An induration of 5 or more millimeters is considered positive for

An induration of 10 or more millimeters is considered positive for

An induration of 15 or more millimeters is considered positive for People with no known risk factors for TB

  • People living with HIV
  • People who have come to the U.S. within the last 5 years from areas of the world where TB is common (for example,
  • Asia, Africa, Eastern Europe, Russia, or Latin America) People who inject illegal drugs
  • Mycobacteriology lab workers  


  • Recent contacts of persons with infectious TB
  • People who live or work in high-risk congregate settings


  • People who have previously had TB disease
  • Patients with organ transplants and other immune suppressed
  • People with certain medical conditions that place them at high risk for TB (silicosis, diabetes mellitus, severe kidney disease, certain types of cancer, and certain intestinal conditions) --Children younger than 4 years --Infants, children, and adolescents exposed to adults in high-risk categories

False-Positive and False-Negative Reactions to the TST

Type of Reaction

Possible Cause

People at Risk


Nontuberculous mycobacteria (NTM)

People infected with NTM

BCG vaccination

People vaccinated with BCG

Administering of  incorrect antigen

Any person being tested

Incorrect interpretation of TST result

Any person being tested



HIV-infected people, other people with weakened immune systems, severe TB disease, and some viral illness (e.g., measles and chicken pox)

Recent TB infection

People infected with M. tuberculosis within the past 8 to 10 weeks

Very young age

Children younger than 6 months

Recent live-virus measles or small pox vaccination

Any person who will be or recently received a live-virus vaccination

Incorrect method of giving TST

Any person being tested

Incorrect interpretation of TST

Any person being tested


The Chest X-Ray (for detail ref to module 12)

The chest x-ray is useful for diagnosing TB disease because pulmonary TB is the most common form of the disease. Usually, when a person has TB disease in the lungs, the chest x-ray appears abnormal.  

Abnormal chest x-ray. Arrow points to cavity in patient’s right upper lobe. Left lung is normal.

Chest x-ray may show

Infiltrates   collections of fluid and cells in the tissues of the lung.
Cavities      hollow spaces within the lung that may contain many tubercle bacilli.

The purposes of the chest x-ray are to

  • Help rule out the possibility of pulmonary TB disease in a person who has a positive TST or a QFT-G result
  • Check for lung abnormalities in people who have symptoms of TB disease

The results of a chest x-ray, however, cannot confirm that a person has TB disease. A variety of illnesses may produce abnormalities whose appearance on a chest x-ray resembles TB.

Although an abnormality on a chest x-ray may lead a clinician to suspect TB, only a bacteriologic culture that is positive for M. tuberculosis proves that a patient has TB disease.

Moreover, a chest x-ray cannot detect TB infection.

In persons living with HIV, pulmonary TB disease may have an unusual appearance on the chest x-ray.

The chest x-ray may even appear entirely normal.

A chest x-ray may be used to rule out the possibility of pulmonary TB in a        person who has had a positive TST result and no symptoms of disease. 


The chest X-ray is no longer the first line investigation for Pulmonary TB and most patients with TB who are diagnosed by sputum smears do not need a chest X-ray.

The chest X-ray appearances are not specific to TB. If X-ray is used as the first line investigation for TB there is a possibility of over diagnosis of TB.
Chest X-ray is only indicated if a patient is found to be sputum smear negative, and there is a need to rule out smear negative pulmonary TB.

Once the results of sputum examination are available, the doctor at GP clinic will make a Diagnosis using following NTP guidelines.

If two or more positive sputum smears
       Declare sputum positive pulmonary TB.

If one sputum positive, Send for X-ray- chest and
      If X-ray consistent with active pulmonary TB.
     Declare sputum positive pulmonary TB.

If X-ray not consistent with active pulmonary TB
   Give antibiotic for 7 days, repeat sputum after 7 days, and re-assess.
   If one or more smear positive, declare sputum positive pulmonary TB.
  If no smear positive, refer to hospital specialist.

If all three sputum smears found negative
Give antibiotic for 7 days, clinically assess after 7 days, send for X-ray (if required).
If X-rays consistent with active pulmonary TB, and patient found still ill.
Declare the patient as sputum negative pulmonary TB.

If X-rays are not consistent with active pulmonary TB
The patient found still ill after taking a full course of antibiotics, then
Refer to hospital for specialist opinion.


Approach To A Patient Based on Sputum Results and Treatment History

Sputum result

Treatment history



Sputum positive

No history of ATT

New case

Start ATT cat 1


ATT taken for recommended period


Start ATT cat 2


ATT not taken for recommended period

Return after default

Start ATT cat 2


Sputum negative

No history of ATT

Non tuberculous etiology

Treatment of the cause

ATT taken for recommended period

Complication of healed TB

Treatment of the cause

ATT not taken for recommended period

Initial diagnosis was based on bacteriological confirmation

Return after default

Treat according to the guidelines

ATT not taken for recommended period

Initial diagnosis was NOT based on bacteriological confirmation

Non tuberculous etiology

Treatment of the cause


Review history of anti tuberculosis Treatment

No previous history of antituberculous treatment:
In such smear negative patients review X-ray chest and first rule out other chronic respiratory disorder

Previous history of anti-tuberculous treatment for recommended period:
The presenting symptoms of such smear negative patient could be due to sequelae of tuberculosis like bronchiectasis, aspergillosis etc.

Previous history of inadequate anti-tuberculosis treatment:                
Stress for previous treatment record for disease classification (pulmonary and extra pulmonary), type of patient (New, relapse, treatment failure etc) sputum results (positive or negative) and duration of ATT. If Patient is presently smear negative and previous treatment was also not based on bacteriological confirmation, first exclude other chronic respiratory disorders

Persistent static shadows or improvement without anti tuberculosis treatment is less likely to be tuberculosis


Differentiating from other common  Chronic Respiratory disorders:
There are many other disorders, which may have clinical presentation similar to tuberculosis such as: 

  1. Post nasal drip (PND)
  2. Gastro esophageal reflux disease (GERD)
  3. Bronchial Asthma
  4. Chronic obstructive pulmonary disease (COPD)
  5. Bronchogenic carcinoma
  6. Bronchiectasis
  7. Fibro cavitary lesion due to any previous illness

These diseases should be managed accordingly. If there is no response in two weeks, refer the patient to tertiary care facility for further investigation.


Salient clinical features differentiating tuberculosis from other possible causes of Chronic Respiratory symptoms

1.Post nasal drip (PND
It is the most common cause of chronic cough,
Clinical features :There is an irritating sensation of having something drip down into the throat   and/or the need to frequently clear the throat, tickling in the throat, or stuffy or dripping nose.
 Physical examination
o secretions and/or cobblestone appearance of  nasop-haryngeal mucosa
Anti histamine, nasal decongestant

2. Gastro esophageal reflux disease (GERD
GERD is caused when reflux of stomach contents leads to symptoms. GERD is a common cause of cough in all age groups.
Clinical features
typical gastrointestinal symptoms (e.g., acid regurgitation,  heart burn)
Modification of lifestyle AND diet.
Avoid ‘hot, spicy and rich’ meals.
Acid suppression, with proton pump inhibitor
If patient respond: Long-term maintenance therapy will be necessary.
If there is no improvement: Refer the patient to gastroenterologist

3.Bronchial Asthma

Clinical features
Cough variant asthma is confused with tuberculosis diagnosis may be suggested by  the cough being brought about by cold air, fumes, fragrances, or exercise.

Physical examination
Wheeze may be present
Peak flow rate before and 20 minutes after β2 agonist can suggest air flow obstruction

Prescribe β2 agonist and steroid as suggested by PCS guide lines
Symptom will start to improve within 1 wk and may take 6–8 wk to resolve. Long-term maintenance therapy with an anti-inflammatory drug may be necessary.
Remember! Asthmatic patient can also have tuberculosis



4.Chronic obstructive pulmonary disease (COPD

Clinical features

History of smoking.
Present with cough and expectoration for many years with/without exacerbations.
x-ray may show emphysematous changes

Cessation of smoking
Prescribe β2 agonist, Ipratropium and steroid as suggested by PCS guide lines

5. Bronchogenic carcinoma
H/o smoking progressive worsening of cough and other sign and symptom
Worsening of radiological shadow
Patient should be referred to tertiary care facility

Clinical features
: history of excessive sputum productionsometimes in copious amounts. The sputum is usually mucoid or mucopurulent ,or  frankly purulent during an exacerbation.
At all times it is thick, tenacious, and difficult to expectorate.
some patients may have dry cough (bronchiectasis sicca).
Reassurance, chest physiotherapy, postural drainage 2nd course of antibiotic covering β-lactamase producing strepto cocci  and gram negative organism for two weeks

7.Fibro cavitary lesion due to any previous illness
Clinical feature
 History of cough preceded by pulmonary problem
persistent static shadow on chest x- ray
Reassurance, chest physiotherapy, postural drainage 2nd course of antibiotic covering β-lactamase producing strepto cocci and gram negative organism for two weeks


Study Questions

Q-1    What are the common signs & symptoms of TB?

Q-2    What are the criteria of TB suspect as per NTP Pakistan?

Q-3    What are the five parts of bacteriological examination for TB diagnosis?

Q-4    What are the methods for obtaining sputum sample?

Q-5    Reading the sputum microscopy result, define the grading?

Q-6    What is the diagnostic importance of TST?

Q-7    What is nucleic acid amplification?

Q-8    What do you mean by NEGATIVE culture?

Q-9    When drug susceptibility testing needed?

Q-10  What are the common abnormalities found in chest x-ray of TB patients?


In this module we will learn about

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