18.01.4.3 Chloramphenicol

The transpeptidation process in bacterial protein synthesis involves an amino acid being added onto a growing peptide chain. This step is inhibited by chloramphenicol. Chloramphenicol is suitable for oral or intravenous use. It is bacteriostatic against most bacteria but does kill Haemophilus influenza. It can also be applied topically, e.g. in ear drops, to treat ear infections. Resistance to chloramphenicol is due to presence of chloramphenicol acetyltransferase produced by resistant strains of Gram-positive and Gram-negative bacteria, and the chloramphenicol acetyltransferase inactivates the chloramphenicol, which obviously reduces the effectiveness of chloramphenicol.

Chloramphenicol is not a very well tolerated drug. It can cause depression of bone marrow leading to pancytopenia (decrease in all elements of blood), which is a serious adverse effect. The use of chloramphenicol is limited, as its benefit must outweigh its risk, for it to be used. Its use it usually in infections which have failed to respond to other antibiotics or cannot be used. For instance, chloramphenicol is used in meningitis when penicillin cannot be used. The adverse effects of chloramphenicol are not an issue when it is used topically.