Mupirocin Calcium

As a member of tRNA synthetase inhibitor antibiotics, it acts on the binding site of isoleucyl-tRNA synthetase and isoleucine in bacterial cells, inhibiting the biosynthesis of isoleucine and depleting intracellular tRNA, thus halting the synthesis of RNA and protein in susceptible bacteria. It shows strong antibacterial activity mainly against aerobic Gram-positive cocci, particularly *Staphylococcus aureus*, *Staphylococcus epidermidis* and *Streptococcus pyogenes* related to skin infections, and is effective against drug-resistant *Staphylococcus aureus* as well. Susceptible Gram-negative bacteria include *Haemophilus influenzae* and *Neisseria gonorrhoeae*. It has weak inhibitory effects on the normal skin flora that form the innate anti-infective barrier, such as *Micrococcus*, *Corynebacterium* and *Propionibacterium*, and no inhibitory effect on *Pseudomonas aeruginosa*, anaerobic bacteria and fungi. With low affinity for mammalian isoleucyl-tRNA synthetase, it has very low toxicity to humans.