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[|Human|] My AFB smear tests #2 are negative. But my chest CT scan show small nodules 0.2 x 0.2 cm in the posterior segment of the right upper lobe and 0.3 x 0.2 cm in the anterior basal segment of the right lower lobe along the inferior major fissure. My pulmonologist thus suspects that I have PTB, and will treat me for this.In other words, the AFB smear tests are not reliable in detecting PTB, am I correct?
[|AI|]  Welcome to Chat Doctor, To diagnose pulmonary Tuberculosis we usually check 2 sputum samples. The first sample is a spot sample and the second is usually a next day morning sample. If any of these or both are positive we start the treatment. If both are negative as in your case, the physicians check for x-ray and if the x-ray is suggestive of Pulmonary Tuberculosis then they can start you on treatment. Some physicians after getting 2 negative samples put their patients on antibiotics and then repeat a 3 sputum sample after 14 days. If it is positive then they start treatment or else they take an x-ray and decide if the person needs treatment or not. Remember sputum test are reliable, but they are not full proof, many patients who are suffering from pulmonary tuberculosis may have negative results, and they are referred to as "sputum smear negative pulmonary tuberculosis"Hope that answers your question.  Chat Doctor. (if the answer has helped you, kindly indicate this)