The sputum test for tuberculosis is negative during the period of taking medicine

A negative sputum test result in a patient with pulmonary tuberculosis while taking anti-tuberculosis drugs does not completely exclude the diagnosis of pulmonary tuberculosis. Because a positive acid-fast sputum smear is one of the important bases for confirming the diagnosis of pulmonary tuberculosis, if the patient is in the early stage of the disease or is in the stable stage, the sputum smear may have a negative acid-fast staining.

1. Reasons

1. Early stage of the disease: the lesions of some patients have not yet formed obvious exudation and caseous necrosis, and the acid-fast staining of sputum smear may not be able to find the abnormality at this time;

2. Stable condition: After a period of standardized anti-tuberculosis treatment, the lesion has been controlled, and there is no new inflammatory infiltration, so the acid-fast staining of the sputum smear may also be falsely negative.

2. Processing

Imaging tests such as chest CT are recommended to determine whether lung lesions are present. If suspicious lesions are present, further biopsy can be performed to aid in diagnosis. For patients with suspected pulmonary tuberculosis, they should continue to take the drug regularly according to the doctor's instructions until a definitive diagnosis is obtained, so as to avoid the exacerbation of the disease and even the development of drug resistance due to self-discontinuation of the drug.

Because tuberculosis is contagious, patients also need to pay attention to isolation and protection, and avoid sharing utensils or close contact with others to avoid cross-infection. At the same time, it is also necessary to regularly review chest X-ray or chest CT and other related examinations to keep abreast of changes in the condition.