Fusidic acid, also known as clostridialic acid, fusidic acid sodium, clostridialic acid sodium, fusidomycin or steroidomycin, is a clostridialic acid antibiotic with steroidal skeleton, its chemical structure is similar to cephalosporin P, not a hormone, produced by fungus in spherical clostridium (Fusidiumcoccineum) or certain cephalosporidium (Cephalosporiumspp). The antibacterial spectrum is narrow and similar to that of neomycin, but the effect on Bacteroidesfragilis is obvious, while the effect on Streptococcusspp and S. pneumoniae is weaker. The mechanism of action is to inhibit the protein synthesis of bacteria and act as an inhibitor or bactericide. It has a strong antibacterial effect on Staphylococcus (including methicillin-resistant strains or other antibiotic-resistant strains), and also has a certain antibacterial effect on Streptococcus, Enterococcus, Diphtheria, Clostridium, Neisseria and Mycobacterium tuberculosis, and a weak effect on Mycobacterium fragilis. Fusidic acid is used for osteomyelitis or skin and soft tissue infections caused by sensitive bacteria. It is also used for deep infections where other antibiotic treatments have failed, such as sepsis, pneumonia, and endocarditis.