Pharmacology Which one of the following is a mechanism underlying the resistance of strains of S. pneumoniae to the widely used antibiotic, ciprofloxacin? A Reduced topoisomerase sensitivity to inhibitors B Increased synthesis of PABA C Formation of methyltransferases that change receptor structure D Structural changes in porins 💡 Explanation Which one of the following is a mechanism underlying the resistance of strains of S. pneumoniae to the widely used antibiotic, ciprofloxacin? ✓ Correct Answer: A. Reduced topoisomerase sensitivity to inhibitors