Scientists have for the first time identified a common skin bacterium --Staphylococcus aureus -- that activates nerve cells in the skin, making people with skin conditions like eczema and atopic dermatitis itch and scratch themselves persistently. In such conditions, the equilibrium of microorganisms that keep our skin healthy is often thrown off balance, allowing S. aureus to flourish, said the researchers from Harvard Medical School

Up until now, the itch that occurs with eczema and atopic dermatitis was believed to arise from the accompanying inflammation of the skin. But the new findings, based on research in mice and in human cells and published in the journal Cell, showed that S. aureus single-handedly causes itch by instigating a molecular chain reaction that culminates in the urge to scratch.