**4. Conclusion**

As microorganisms have close and complex relationships with human skin, doctors and scientists should be aware of the presence of good and harmful species in the skin. Human skin has mechanisms to allow microbes to reside on the skin, and good microbes may help humans.

On the other hand, certain microbes may trigger AD under certain conditions and others are consistent pathogens. When considering microorganisms as exacerbating factors, research should be performed in order to clarify their roles. Such research may lead to advances in the treatment and prevention of AD.

In treatment of various infectious conditions in AD patients, careful and well-considered strategy by dermatologists is necessary.
