Which statement about antibiotic spectra is correct?

• A. Broad-spectrum antibiotics affect a narrow range of bacteria.
• B. Narrow-spectrum antibiotics target specific groups or species.
• C. Broad-spectrum antibiotics target viruses.
• D. Narrow-spectrum antibiotics kill fungi.

Answer: (B)

Antibiotic spectrum describes the range of bacteria that an antibiotic can affect. Narrow-spectrum antibiotics target specific groups or species, which is why this statement is the best description. When you know the pathogen, using a narrow-spectrum agent helps limit disruption to the patient’s normal flora and reduces the chance of resistance development, compared with broad-spectrum drugs that act on a wider range of bacteria. Broad-spectrum antibiotics do not target viruses—antibiotics act on bacteria, while antiviral drugs handle viruses—and they also do not kill fungi, which require antifungal medications. So the accurate description is that narrow-spectrum antibiotics target specific groups or species.