All kinds of bacteria live in different environments and spread through different routes. According to incomplete statistics, in the upper body of the human body, there are 50-5000 microorganisms on the average per square centimeter of skin, which obtain nutrients from the sweat and secretions of the human body and carry out the metabolism of growth, reproduction and death. The fatty acids and lactic acid in sweat or secretions can kill a variety of microorganisms, and the microorganisms also have the effect of killing or inactivating each other, constituting the coordination and balance of nature.

There are a small number of pathogenic bacteria in the microorganisms, and the fungi that have infringed on the skin have skin filamentous bacteria (shallow invasion), which multiply rapidly under humid conditions with more secretions, exceeding the number of other microorganisms, forming bacterial imbalance, encroachment on the superficial part of the skin, causing eczema, athlete's foot, tinea capitis; Candida albicans (deep invasive) can cause thrush, candida enteritis, esophagitis, vaginitis, bronchitis, pneumonia, cystitis, pyelonephritis, septicemia, endocarditis, meningitis and other diseases in children. Staphylococcus aureus can cause furuncle, carbuncle, pemphigus neonatorum, acute mastitis, abscess otitis media and other diseases in the skin where there are lacerations or wounds, sweat glands and hair follicles. The pus is yellow, and staphylococcus aureus can cause septicemia when it invades the blood. Pseudomonas aeruginosa can infect burns and invade wounds, necrotic skin and flesh, and the pus is green. Bacteria that live on the surface of the skin are mostly transmitted by contact and can cause surgical diseases when conditions are right.

In addition, there are some parasitic in other parts of the human body a variety of pathogenic bacteria, such as respiratory tract pathogenic bacteria are: live in the nasopharynx streptococcus vireus and amygtococcus, mycoplasma pneumoniae, meningococcus, influenza bacillus in the body, they are carried out from mucus, sputum, sneezing, contaminated on a variety of objects to spread; Pathogenic bacteria of the digestive tract include: typhoid and dysentery bacilli, which are mainly transmitted to food through flies, dust, etc., and then invade the digestive tract; Escherichia coli can cause urethritis, cystitis and pyelonephritis when it enters urinary system. The pathogenic bacteria of eye were chlamydia trachomatis, inclusion bodies, conjunctivitis; Sexually transmitted bacteria are: subtilis, this type of bacteria is also contagious.

Pathogenic bacteria include direct transmission and indirect transmission. Healthy carriers refer to those who are infected with pathogenic bacteria and do not get sick themselves, but bring diseases to people with weak resistance, or the pathogenic bacteria temporarily fall on clothes, shoes and hats, handkerchiefs, towels, bedding, sheets, sofa covers, gauze, bandages, and human hands, faces and hair. Then transfer to their own or someone else's body parts suitable for the reproduction of the pathogen and cause disease. Whether it is direct or indirect transmission, textiles are an important medium, if the textile has the function of killing pathogens, it not only reduces an important route of transmission, but also prevents bacteria from constantly multiplying on the fabric and producing odor.