*2.8.1 Mechanism of action*

It was isolated from a strain of *Fusidium coccineum*, which is a steroid like antibiotic. It is mainly bacteriostatic in nature but may become bactericidal at higher concentrations. It acts by binding with Elongation factor G i.e. Translocase which is necessary for translocation on the bacterial ribosome after peptide bond formation during protein synthesis. However eukaryotes have another enzyme which is not affected by the drug. This specific mode of action explains the absence of intrinsic cross- resistance between Fusidic acid and other antibiotics. It has a limited spectrum of activity, mainly against Gram positive bacteria i.e. *Staphylococcus aureus, S.epidermidis, Clostridium spp. and Corynebacterium*. However, *Streptococci* are moderately susceptible. But most Gram Negative Bacteria are resistant to it [60].
