What is the major difference between narrow-spectrum antibiotics and broad-spectrum antibiotics?

• A. Narrow-spectrum target specific organisms.
• B. Broad-spectrum affect a wide range of bacteria, increasing resistance risk.
• C. Narrow-spectrum have no side effects.
• D. Broad-spectrum are always ineffective.

Answer: (A)

Narrow-spectrum antibiotics are defined by their targeted action, working against specific organisms or groups of organisms. This makes them ideal when the causative bacteria are known, because they attack the pathogen while leaving many other bacteria unharmed, reducing collateral damage and helping limit resistance. Broad-spectrum antibiotics, on the other hand, affect a wide range of bacteria, which is useful when the exact pathogen isn’t known or there are multiple organisms involved, but their broad activity can disrupt normal flora and promote resistance. So the key difference is the range of bacteria they affect. Statements about no side effects or being always ineffective aren’t about this defining feature.