Chloramphenicol is a chlorine-containing antibiotic produced by Streptomyces venezuelae. It has a wide spectrum of activity against gram-positive and gram-negative cocci and bacilli (including anaerobes), Rickettsia, Mycoplasma and Chlamydia. It inhibits prokaryotic protein synthesis by attaching to the 50S ribosomal subunit. This inhibits peptidyltransferase, thereby preventing the formation of peptide bonds. It also inhibits protein synthesis in mitochondria which accounts for its toxic effects that cause aplastic anemia. Chloramphenicol has other adverse effects such as bone marrow depression and gray baby syndrome. It