A drug is structurally similar to PABA and inhibits folic acid synthesis. It is most likely a (n)

a. penicillin

b. nucleic acid analog

c. tetracycline

d. azole

e. sulfonamide

e. sulfonamide

Explanation:

Sulfonamides are man made antimicrobial agents which are structural analogs of PABA (para-aminobenzoic acid). PABA is an intermediate stage in folate synthesis process by bacteria. Since sulfonamide is structurally similar to PABA, it interferes with the activity of enzyme dihydropteroate synthetase whose function is to convert PABA to folate. Hence, bacterial growth is restricted due to folate deficiency.

Sulfonamide is also used against some protozoans like Plasmodia and Toxoplasma. It is used mostly to treat urinary tract infections. It can also be used in combination with other drugs. However rising resistance to it is an issue.