These proteins promote bacterial spread out in host tissues. _-toxin (_-haemolysin) is the best known membrane damaging protein, platelets and monocytes display specific receptors for this toxin that, once bounded, provokes the making of pores consenting the passage of monovalent cations and consequently causing cell's osmotic lysis. _-toxin is a sphyngomyelinase whose target is rich-in-lipids membranes and is quite rare in front of _- toxin, a little peptide also produced by S. epidermidis and whose action in diseases is already unknown. Leukocidin is a toxin originated from the protein components B and C expressed by the _-toxin locus, this toxic agent has poor haemolytic activity because only the B subunit (as on the other hand the subunit A) has haemolytic properties. Leukocidin has an octameric structure constituted by 4 LukF and 4 LukS subunits that together form damaging membrane pores. Leukocidin production is quite rare and verifiable in approximately 2% of S. aureus strains but inside this portion, its presence reach 90% in severe dermonecrotic lesions, confirmation of its important role in necrotizing skin infection also emphasized by concomitant inflammatory mediators release that provoke vasodilatation, infiltration and progressively lead to tissue degranulation.