What tests should be done for tuberculosis

Tuberculosis usually requires sputum smear examination, sputum culture examination, chest X-ray or CT examination, tuberculin test, and molecular biology testing. Tuberculosis is a chronic respiratory infectious disease caused by Mycobacterium tuberculosis. Timely examination can help clarify the diagnosis and guide treatment.

1. Sputum smear examination:

Sputum smear examination is one of the most commonly used methods for diagnosing pulmonary tuberculosis, which is determined by directly observing whether acid fast bacilli are present in sputum. This type of inspection operation is simple and fast, and usually results can be obtained within one to two days. If the result is positive, it may indicate the presence of Mycobacterium tuberculosis infection, but a negative result cannot completely rule out pulmonary tuberculosis because some patients have lower bacterial output.

2. Sputum culture examination:

Sputum culture examination is the gold standard for diagnosing pulmonary tuberculosis, which can determine the presence of Mycobacterium tuberculosis and perform drug sensitivity tests. Sputum culture requires placing sputum samples in a specific culture medium to observe bacterial growth, which usually takes four to eight weeks to obtain results. This method has high sensitivity and is particularly suitable for patients with negative sputum smears but high clinical suspicion of tuberculosis.

3. Chest X-ray or CT examination:

Chest X-ray examination can display the morphology, scope, and location of lung lesions, and is an important means of screening for tuberculosis. Typical manifestations include infiltrative shadows in the upper lung field, formation of cavities, or fibrous cord shadows. Chest CT examination is more accurate than X-ray and can detect small or hidden lesions, which is of great value for diagnosing atypical pulmonary tuberculosis or evaluating treatment effectiveness. These two types of examinations are non-invasive and convenient, and are indispensable imaging methods in the diagnosis of pulmonary tuberculosis.

4. Tuberculin test:

Tuberculin test, also known as PPD test, determines whether tuberculosis is infected by injecting tuberculin intradermally into the forearm and observing local skin reactions. A positive result in this test indicates previous infection with tuberculosis or vaccination with BCG, but cannot distinguish between active tuberculosis and latent infection. For children or individuals with low immune function, the tuberculin test may result in a false negative and require a comprehensive assessment in conjunction with other tests.

5. Molecular Biology Testing:

Molecular biology testing such as XpertMTB/RIF technology can quickly obtain results within one to two hours by detecting Mycobacterium tuberculosis DNA in sputum, and can also detect rifampicin resistance simultaneously. This type of examination has high sensitivity and strong specificity, especially suitable for early diagnosis of sputum smear negative or drug-resistant tuberculosis. The World Health Organization recommends it as the preferred molecular testing method for the diagnosis of tuberculosis. When undergoing tuberculosis examination, it is recommended that patients go to regular medical institutions and have doctors select appropriate examination items based on symptoms and signs. Daily attention should be paid to maintaining indoor ventilation, wearing masks, and avoiding close contact with others. After diagnosis, patients should follow medical advice for standardized treatment, adhere to complete the entire medication process, regularly check sputum and imaging changes, and pay attention to supplementing nutrition and taking appropriate rest to promote recovery.