Disadvantage of INH prophylaxis are all of the Following except
**Core Concept**
Prophylactic use of isoniazid (INH) is a strategy to prevent tuberculosis (TB) in individuals exposed to the disease, particularly in high-risk populations such as healthcare workers and close contacts of TB patients. This approach aims to reduce the risk of latent TB infection progressing to active TB disease.
**Why the Correct Answer is Right**
Isoniazid prophylaxis is effective in preventing the progression of latent TB infection to active TB disease, but it has several disadvantages. One significant drawback is the risk of hepatotoxicity, which can be severe and potentially life-threatening. This is due to the metabolism of INH, which involves the enzyme N-acetyltransferase 2 (NAT2), and the subsequent formation of toxic metabolites that can damage liver cells. Additionally, INH can also cause peripheral neuropathy, particularly in individuals with a deficiency of vitamin B6, which is necessary for the metabolism of INH.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because INH resistance is a potential consequence of INH prophylaxis, particularly if the regimen is not properly monitored. Resistance can develop due to the selection of INH-resistant strains of Mycobacterium tuberculosis.
**Option B:** This option is incorrect because INH prophylaxis is not effective in preventing the transmission of TB to others. The use of INH prophylaxis is primarily focused on preventing the progression of latent TB infection to active TB disease in the individual being treated.
**Option C:** This option is incorrect because INH prophylaxis does not provide long-term protection against TB. The protective effect of INH prophylaxis is typically short-lived, and individuals may still be at risk of developing active TB disease if exposed to the bacteria.
**Option D:** This option is incorrect because INH prophylaxis is not associated with an increased risk of TB meningitis. However, INH can cause a range of other side effects, including hepatotoxicity, peripheral neuropathy, and rash.
**Clinical Pearl / High-Yield Fact**
It's essential to monitor patients receiving INH prophylaxis for signs of hepatotoxicity, such as elevated liver enzymes, and to advise them to report any symptoms of peripheral neuropathy, such as numbness or tingling in the hands and feet.
**Correct Answer: B. INH prophylaxis is not effective in preventing the transmission of TB to others.**