Also known as Neurodermatitis, atopic dermatitis (AD) mostly affects children and is a very unpleasant chronic infection of the skin. A dramatic dysbiosis plays a role in this disease. The question is, what came first: the inflammation of the skin or the infection with Staphylococcus aureus? A dramatic overabundance of S. aureus (90%) on affected but also on unaffected skin of AD patients may lead to the conclusion that latter is correct. In healthy individuals, S. aureus is very rarely found on the skin. The dominant S. aureus in AD patients monopolizes the space and nutrients of all the other good commensals which would in fact eventually kill this bug. Interestingly S. epidermidis is also found more often in AD patients than in healthy persons, suggesting that S. epidermidis recruited its army to fight against S. aureus, but this still is only an assumption.
Many of us know this skin disease from puberty – and we were not alone; 85% of teenagers are affected by acne. The bacterium which tortures us during our teens is Cutibacterium acnes, which formerly lived with us in peaceful symbiosis. With the onset of puberty, the chemical composition of the skin, primarily in the face, undergoes changes due to the hormonal shift. These changes cause a battle between the immune system and the Cutibacterium, leading to infected sebaceous glands and thus acne. Scientist must further investigate whether there is a special C. acnes species that is responsible for acne that differs from our commensal friends… we're especially excited for new findings here!