How does INH primarily affect bacteria?

The correct answer revolves around the role of isoniazid (INH) in treating bacterial infections, specifically those caused by Mycobacterium tuberculosis. Isoniazid is an antibiotic that works by inhibiting the synthesis of mycolic acid, which is a critical component of the bacterial cell wall in mycobacteria. Mycolic acids are long-chain fatty acids that play a vital role in maintaining the structural integrity and impermeability of the bacterial cell wall, making it essential for the bacteria's survival and virulence.

By targeting the enzyme involved in the biosynthesis of mycolic acids, isoniazid effectively prevents the bacteria from forming a robust cell wall. This disruption leads to bactericidal effects, as a compromised cell wall cannot protect the bacteria from osmotic pressure and other environmental stresses, ultimately leading to cell death. Therefore, the efficacy of INH in treating tuberculosis is heavily reliant on its ability to interfere with mycolic acid metabolism, highlighting the significance of this mechanism in antimicrobial therapy for mycobacterial infections.