Chloramphenicol - Definition and Overview

Chloramphenicol is an antibiotic that was derived from the bacterium Streptomyces venezuelae and is now produced synthetically. Chloramphenicol is effective against a wide variety of microorganisms, but due to serious side-effects (e.g., damage to the bone marrow, including aplastic anemia) in humans, it is usually reserved for the treatment of serious and life-threatening infections (e.g., typhoid fever). It is also used in eye drops or ointment to treat bacterial conjunctivitis.

C₁₁H₁₂C_l2N₂O₅ Chloramphenicol M_W=323.13

(2,2-Dichlor-N-[(aR,bR)-b-hydroxy-a-hydroxymethyl-4-nitrophenethyl]acetamid)
Image in the PD.

Mechanism and Resistance

Chloramphenicol stops bacterial growth by binding to the bacterial ribosome and inhibiting protein synthesis.

Resistance to chloramphenicol is conferred by the cat-gene. This gene codes for an enzyme called "chloramphenicol acetyltransferase" which inactivates chloramphenicol by covalently linking one or two acetyl groups, derived from acetyl-S-coenzyme A, to the hydroxyl groups on the chloramphenicol. The acetylation prevents chloramphenicol from binding to the ribosome.