As we know, the pathogenic microorganisms have to rely on certain media in the external environment to discharge from the source of infection into human body. In daily life, our hands have the most opportunity to contact various items, so the hand is considered as the most direct pathogenic microorganisms media. Therefore, people have to wash hand frequently.
According to statistics, there are average ten thousand micro-organisms per square centimeter of human skin, particularly in skin folds and fingers. In addition to skin surface, parasites also exist in sweat glands, hair follicles, and sebaceous glands. According to the parasitism degrees of bacteria, they can be divided into transient bacteria and resident bacteria.
Transient bacteria exist on the skin surface and they are remained on the skin because of the skin contact with other items. The number and types of such bacteria is changeable, which is related with the contact times, pollution degree and clean habits. Parts of transient bacteria can result diseases such as E. coli and Staphylococcus aureus. Their survival time is generally less than 24 hours and they can be removed by washing hands with soap.
The type and number of resident bacteria is relatively constant, many of which are non-pathogenic bacteria. They can survive and reproduce on the skin. They exist in the deep of skin and cannot be removed with soap. If people do not clean hand skins for long time, the transient bacteria can transfer into resident bacteria. So, the function of hand washing is to reduce or eliminate pathogenic bacteria effectively.
Washing hands with soap can clear 60% to 90% microorganisms on keratinized epithelium. Although this method cannot remove all transient bacteria on hands, it can reduce the amount of bacteria under the infection number. After contacting with infectious patients and their items, it is better to use 75% alcohol to wipe hands for 1 minute. It is the simplest and quickest way.