What is the mechanism of action of fluoroquinolones and which PK/PD index most closely predicts efficacy?

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Multiple Choice

What is the mechanism of action of fluoroquinolones and which PK/PD index most closely predicts efficacy?

Fluoroquinolones kill bacteria by blocking two essential DNA-processing enzymes: DNA gyrase (topoisomerase II) and topoisomerase IV. This prevents proper DNA supercoiling and separation, stopping replication and transcription and leading to bacterial death. Because their effect depends on sustained exposure to the antibiotic, the best predictor of efficacy is the AUC/MIC—the total drug exposure over time relative to the MIC. This captures both how strong the drug is and how long the pathogen sees the drug. While Cmax/MIC can influence the speed of kill, and time above MIC matters for other drug classes, AUC/MIC is the most reliable PK/PD correlate for fluoroquinolones.

Fluoroquinolones kill bacteria by blocking two essential DNA-processing enzymes: DNA gyrase (topoisomerase II) and topoisomerase IV. This prevents proper DNA supercoiling and separation, stopping replication and transcription and leading to bacterial death. Because their effect depends on sustained exposure to the antibiotic, the best predictor of efficacy is the AUC/MIC—the total drug exposure over time relative to the MIC. This captures both how strong the drug is and how long the pathogen sees the drug. While Cmax/MIC can influence the speed of kill, and time above MIC matters for other drug classes, AUC/MIC is the most reliable PK/PD correlate for fluoroquinolones.

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