Sulfonamides are broad spectrum antibiotics.

• A. True
• B. False
• C. Not sure
• D. Only in combination

Answer: (A)

Sulfonamides are broad spectrum because they block folic acid synthesis, a pathway present in a wide range of bacteria. This makes them active against many Gram-positive and Gram-negative organisms, giving broad coverage for various infections. Mammals don’t synthesize folate, so they’re less affected, which explains the selective toxicity. In practice, sulfonamides are often used alone for broad empirical coverage or combined with trimethoprim to widen and strengthen the effect by hitting a second step in the same pathway, reducing resistance and increasing potency. However, some pathogens are not susceptible, and resistance can occur, so susceptibility matters. Overall, the class is considered broad spectrum, so the statement is true.