50 year old, Rishi has a diagnosis of pulmonary tuberculosis. How many infectious nuclei per cough are likely to be seen in sputum examination?
**Core Concept**
Pulmonary tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis (M. tuberculosis). The infectiousness of TB is determined by the number of viable bacteria in the sputum. In the early stages of TB, the number of infectious bacteria can be high, but it decreases as the disease progresses.
**Why the Correct Answer is Right**
The correct answer is based on the fact that in the early stages of pulmonary TB, the number of infectious bacteria in the sputum can be as high as 10,000 to 100,000 bacteria per cough. This is because the bacteria are actively multiplying and are more likely to be coughed up. However, as the disease progresses and the host's immune system responds, the number of infectious bacteria decreases. In the later stages of TB, the number of infectious bacteria may be as low as 10 to 100 per cough.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is too low. In the early stages of TB, the number of infectious bacteria is typically much higher than 10 per cough.
**Option B:** This option is incorrect because it is too high. In the later stages of TB, the number of infectious bacteria is typically much lower than 100,000 per cough.
**Option C:** This option is incorrect because it is a range, but it is not a specific number. The correct answer is a specific number that is commonly cited in medical literature.
**Option D:** This option is incorrect because it is not a valid number. It is possible that the question is trying to trick the test-taker with a made-up number.
**Clinical Pearl / High-Yield Fact**
It's essential to note that the infectiousness of TB can vary widely from person to person and can depend on various factors, including the stage of the disease, the effectiveness of the host's immune response, and the presence of other medical conditions.
**Correct Answer:** C. 10,000.