• Laura Chaparro, science journalist

    Skin flora, our protective shield

    4 Feb

    The flora of our skin is made up of millions of bacteria that live in harmony with us. Thanks to this flora we have a shield that protects us, as the bacteria ward off infection and ensure that our skin stays healthy and attractive.


    When we hear the word 'bacteria' we think of harmful microorganisms responsible for infections. And while it is certainly true that bacteria can cause infection, this is more the exception than the rule. The bacteria and fungi resident in our skin are part of our normal microbial flora and perform very important functions. In addition to self-regulation that maintains the body’s equilibrium, the flora protects us against infection and enhances the skin’s barrier function by breaking down skin surface lipids. The flora is also responsible for our body's natural odour, caused by bacteria breaking down the components in sweat. 
    The flora keeps our skin balanced, healthy and attractive. And although this is a natural process, we can help the flora by hydrating the skin. We should also pay particular attention to the pH level in our daily hygiene products, as it has been found that slightly acidic pH levels help maintain the skin flora.


    Where is the flora?
    A single fact proves the flora’s benevolence: we typically host a fairly constant 10–14 (ten to the power of 14, or one followed by 14 zeros) bacteria in our normal microbial flora. Skin flora bacteria are located on the surface of the skin in the stratum corneum, sebaceous glands and hair follicles. Only when our defences are low or when the skin is damaged is our beneficial relationship with bacteria altered, leading to a medical condition.


    Are staphylococci harmful?
    Within the vast bacterial community that we play host to, one family of organisms is a source of concern for the infections that it can cause. The bacteria are called staphylococci, and Staphylococcus aureus is the most common cause of staph infections. If our skin is healthy, hydrated and acid-balanced these bacteria are harmless. But when the skin is damaged or is undernourished, these bacteria can cause problems such as boils or infectious cellulitis (not to be confused with common or fatty cellulite). However, a recent study by the University of California at San Diego (USA), published in Nature Medicine, reveals that some of our flora actually inhibits staphylococcal inflammation of the skin.


    We are born without flora
    Our skin flora, therefore, plays a crucial role; however, a baby’s skin is only colonized after birth. Although the foetus is free of microorganisms in the womb, once the mother breaks water the womb is no longer sterile. Babies develop their own stable community of flora in the oral cavity, gastrointestinal tract and skin, but only by 48 hours after birth. The intervening period is thus vital for proper infant development, which is why hospitals pay special attention to ensuring that bacterial infections are not transmitted to newborn babies.