Mechanism of R factor-mediated chloramphenicol resistance

Abstract

The R+ strains of Escherichia coli with chloramphenicol resistance determinant, inactivate the antibiotic in the presence of acetyl-coenzyme A (acetyl-CoA). Chloramphenicol resistant R factor strains of E. coli inactivate the antibiotic by enzymatic acetylation. Chemical isolates of enteric bacteria with an R factor for chloramphenicol resistance contain the enzyme chloramphenical acetyl-transferase. The impermeability of strain 222/CSH-2 is due to failure of chloramphenicol-3-acetate to bind to the bacterial ribosomes, resulting in no accumulation of radioactivity within resistant cells as compared with the sensitive cells which lack the acetylating enzyme.