During pharmacology class, a nursing professor poses the following question: "We have learned that certain medications, such as fluoroquinolones, are effective because they inhibit bacterial DNA replication

Question

Why don't these medications cause harm to the nonbacterial cells in the body?" Which student nurse answered the question correctly?
1. Student B: "Medications such as fluoroquinolones do not appear to affect human DNA because human DNA is very similar to bacterial cell DNA."
2. Student D: "Human DNA is inherently healthier than bacterial DNA, so medications such as fluoroquinolones do not affect their replication."
3. Student C: "Medications such as fluoroquinolones don't appear to affect human DNA replication because of the difference between the enzymes needed for bacterial and human DNA replication."
4. Student A: "These medications protect healthy human cells while they attempt to disrupt bacterial DNA replication."

Answer 1

Correct Answer: 3
Rationale 1: Human DNA and bacterial DNA have vastly different enzymes necessary for replication.
Rationale 2: Fluoroquinolones affect enzymes needed for bacterial DNA replication, and they do not target the enzymes present in human DNA cells. There is no indication that human DNA is healthier than bacterial DNA.
Rationale 3: It is thought that medications such as fluoroquinolones are very safe to use because they do not affect human DNA replication. This is because the enzymes that the medications affect in bacterial DNA replication are very different from the enzymes present in human DNA cells.
Rationale 4: Fluoroquinolones offer no protection to human DNA. They do not affect human DNA replication because the enzymes needed for human DNA replication are different from the enzymes needed for bacterial DNA replication.
Global Rationale: These drugs have no effect on human enzymes involved in DNA replication because of significant differences in the chemical structures of the human and bacterial enzymes. These differences account for their selective toxicity on bacteria, and their favorable safety profile. The statement regarding DNA health is inaccurate. These drugs offer no protection to human DNA.