Daptomycin is a member of the A 21978 complex of high molecular weight cyclic lipopeptides with potent antibiotic activity, notably against MRSA, VISA and VRSA bacterial strains. Originally isolated from Streptomyces roseosprous by Eli Lily in the 1980s, daptomycin was selected and developed by Cubist Pharmaceuticals for human use. Daptomycin exhibits Ca-dependent depolarisation of the bacterial membrane resulting in loss of membrane potential leading to inhibition of DNA, RNA and protein synthesis which results in cell death.