Pharmacology The most important mechanism by which gram negative bacilli acquire chloramphenicol resistance is: A Decreased permeability into the bacterial cell. B Acquisition of a plasmid encoded for chloramphenicol acetyl transferase. C Lowered affinity of the bacterial ribosome for chloramphenicol. D Switching over from ribosomal to mitochondrial protein synthesis. 💡 Explanation The most important mechanism by which gram negative bacilli acquire chloramphenicol resistance is: ✓ Correct Answer: B. Acquisition of a plasmid encoded for chloramphenicol acetyl transferase.