Chloramphenicol and tetracycline (broad spectrum antibiotics)

Broad-spectrum antibiotics such as tetracycline and chloramphenicol bind to the elongating ribosome and prevent the transfer of the ternary complex aminoacylated-tRNA and EF-Tu, GTP to the A-site. Tetracycline's major binding site is in the 30S subunit's helix 34 (h34) of the 16S rRNA, which overlaps the anticodon stem loop of the A-site tRNA. Tetracycline and Chloramphenicol has been widely used in both animals and people for the past 60 years, resulting in a surge in tetracycline resistance. Tetracycline resistance is caused through the acquisition of novel genes that code for energy-dependent tetracycline efflux, a protein that shields bacterial ribosomes from tetracycline action or enzymatic inactivation, and a protein with unclear mode of action. Chloramphenicol resistance is caused by chloramphenicol acetyltransferases, which render chloramphenicol inert. There are two varieties of CAT enzymes, each of which is genetically distinct. Chloramphenicol might possibly be attributed to chloramphenicol efflux via membrane-associated transporters. Both the genes coding for CATs and particular exporters are frequently connected with mobile elements such as plasmids, transposons, or gene cassettes and can be transmitted between bacteria of different species and genera by conjugation, mobilization, transduction, or transformation. Chloramphenicol-exporting chromosomal multidrug transporters have also been discovered. Chloramphenicol can also be caused by mutations that diminish outer membrane protein production, alterations in the 23S rRNA, 3-O-phosphotransferase inactivation of chloramphenicol, or target site modification by a 23S rRNA methylase.