The TB culture and sensitivity test is a laboratory test used to identify and determine the susceptibility of Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB), to different antibiotics.

Pre-test preparation: No special preparation is needed for the TB culture and sensitivity test.

Testing method: A sample of sputum, bronchial washings or pleural fluid is collected from the patient. The sample is then placed on a solid medium that supports the growth of Mycobacterium tuberculosis. The culture is incubated at a specific temperature for several weeks. Once the bacteria have grown, they are identified by staining and examined under a microscope. Antibiotic susceptibility testing is then performed on the culture to determine which antibiotics the bacteria are sensitive or resistant to.

Common symptoms for prescribing this test: TB culture and sensitivity test is usually ordered when a patient has symptoms of TB such as a persistent cough, chest pain, shortness of breath, fever, night sweats and weight loss.

Diagnosis: A positive culture for Mycobacterium tuberculosis confirms the diagnosis of TB, and the antibiotic susceptibility testing results help the healthcare provider to choose the appropriate antibiotics for the treatment.

Reference range: Negative for Mycobacterium tuberculosis
Normal values: Negative for Mycobacterium tuberculosis

It is important to note that TB culture and sensitivity test is a confirmatory test, other tests such as chest X-ray, sputum smear microscopy, and PCR should be used to support the diagnosis of TB. Also, the results of the test should be considered along with the patient’s clinical presentation and other laboratory test results to arrive at an accurate diagnosis.