Within a Staphylococcus aureus biofilm treated with ciprofloxacin, which mutational mechanism most directly enables increased antibiotic resistance?

💡 Explanation

A mutation altering a DNA gyrase subunit directly impacts ciprofloxacin's target, because ciprofloxacin inhibits DNA gyrase, preventing DNA replication and bacterial proliferation; therefore, a mutation reducing the drug's binding affinity increases resistance, rather than solely modifying the cell wall or capsule.

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