Which antibiotic class inhibits folic acid synthesis?

The antibiotic class that inhibits folic acid synthesis is sulfonamides. This class works by mimicking para-aminobenzoic acid (PABA), which is a substrate required for the bacterial synthesis of folate. By competitively inhibiting the enzyme dihydropteroate synthase, sulfonamides disrupt the production of folic acid, which is crucial for DNA synthesis and ultimately for bacterial growth and reproduction.

In contrast, penicillins and cephalosporins are beta-lactam antibiotics that primarily target bacterial cell wall synthesis, leading to cell lysis. Aminoglycosides, on the other hand, interfere with protein synthesis by binding to the bacterial ribosome. Since folic acid synthesis is vital for many bacterial species, the inhibition by sulfonamides renders them effective against a range of infections.