An antibiotic that inhibits protein synthesis by binding to the 50s ribosomal subunit and blocking the peptidyltransferase reaction. Chloramphenicol resistance encoded by many plasmids (e.g. pBR328) is due to a cytoplasmic chloramphenicol acyltransferase which inactivates chloramphenicol by covalently acetylating it.

Chloramphenicol is a bacteriostatic antibiotic originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949.