Human skin and mucous membranes are colonized by different bacteria (e. g. in digestive tract and genital tract) which are responsible for the skin’s health and maintenance of natural functions. Various lactic acid bacteria are responsible for the production of lactic acid. The low pH value between 3 and 4 in the genital area protects against pathogenic microorganisms. This acidic milieu is unfavourable for the growth of common pathogens, thus they cannot reach the upper genital area. For comparison: the skin’s pH value is about 5,5. These lactic acid bacteria in the female genital tract are called “bacteria of Doederlein”, they form the characteristic bacterial flora of the female genital tract. They produce and maintain the natural lactic acid protection system of the female genital tract.