Broad-spectrum antibiotics have a wide variety including Gram-positive and Gram-negative bacteria. Which statement best describes this spectrum?

• A. They target only Gram-positive bacteria
• B. They target only Gram-negative bacteria
• C. They target a wide variety including both Gram-positive and Gram-negative bacteria
• D. They are ineffective against anaerobes

Answer: (C)

Broad-spectrum antibiotics are active against a wide range of bacteria, not just one group. They achieve this by targeting mechanisms or structures that are common across many organisms and by having properties that allow them to reach and affect diverse bacterial types. Because of this broad activity, they typically cover both Gram-positive and Gram-negative bacteria, and often some also cover anaerobes. That makes the statement describing a wide variety including both Gram-positive and Gram-negative bacteria the best description. In contrast, saying they target only one Gram type describes narrow-spectrum agents, and claiming they are ineffective against anaerobes isn’t accurate for many broad-spectrum drugs.