to colonisation by s. aureus and following standard treatment, bacterial diversity has been seen to increase. current treatments include combinations of topical or systemic antibiotics, corticosteroids, and diluted bleach baths. potential probiotic treatments include using the commensal skin bacteria, s. epidermidis, to inhibit s. aureus growth. during atopic dermatitis flares, population levels of s. epidermidis has been shown to increase as an attempt to control s. aureus populations. low gut microbial diversity in babies has been associated with an increased risk of atopic dermatitis. infants with atopic eczema have low levels of bacteroides and high levels of bacillota. bacteroides have anti-inflammatory properties which are essential against dermatitis. (see gut microbiota) psoriasis vulgaris psoriasis vulgaris typically affects drier skin sites such as elbows and knees. dry areas of the skin tend to have high microbial diversity and fewer populations than sebaceous sites. a study using swab sampling techniques show areas rich in bacillota (mainly streptococcus and staphylococcus) and actinomycetota (mainly corynebacterium and propionibacterium) are associated with psoriasis. while another study using biopsies associate increased levels of bacillota and actinomycetota with healthy skin. however most studies show that individuals affected by psoriasis have a lower microbial diversity in the affected areas. treatments for psoriasis include topical agents, phototherapy, and systemic agents. current research on the skin microbiota's role in psoriasis is inconsistent therefore there are no potential probiotic treatments. rosacea rosacea is typically connected to sebaceous sites of the skin. the skin mite demodex folliculorum produce lipases that allow them to use sebum as a source of food therefore they have a high affinity for sebaceous skin sites. although it is a part of the commensal skin microbiota, patients affected with rosacea show an increase in d. folliculorum compared to healthy individuals, suggesting pathogenicity. bacillus oleronius, a demodex associated microbe, is not typically found in the commensal skin microbiota but initiates inflammatory pathways whose starting mechanism is similar to rosacea patients. populations of s. epidermidis have also been isolated from pustules of rosacea patients. however it is possible that they were moved by demodex to areas that favour growth as demodex has shown to transport bacteria around the face. current treatments include topical and oral antibiotics and laser therapy. as current research has yet to show a clear mechanism for demodex influence in rosacea, there are no potential probiotic treatments. clinical infected devices skin microbes are a potential source of infected medical devices such as catheters. hygiene the human skin is host to numerous bacterial and fungal species, some of which are known to be harmful, some known to be beneficial and the vast majority unresearched. the use of bactericidal and fungicidal soaps will inevitably lead to bacterial and fungal populations which are resistant to the chemicals employed (see drug resistance). contagion skin flora do not readily pass between people: 30 seconds of moderate friction and dry hand contact results in a transfer of only 0.07% of natural hand flora from naked with a greater percentage from gloves. removal the most effective (60 to 80% reduction) antimicrobial washing is with ethanol, isopropanol, and n-propanol. viruses are most affected by high (95%) concentrations of ethanol, while bacteria are more affected by n-propanol. unmedicated soaps are not very effective as illustrated by the following data. health care workers washed their hands once in nonmedicated liquid soap for 30 seconds. the students/technicians for 20 times. skin flora upon two hospital groups in colony-forming units per ml. group and hand skin condition unwashed washed health care workers healthy 3.47 3.15 health care workers damaged 3.33 3.29 students/technicians healthy 4.39 3.54 students/technicians damaged 4.58 4.43 an important use of hand washing is to prevent the transmission of antibiotic resistant skin flora that cause hospital-acquired infections such as methicillin-resistant staphylococcus aureus. while such flora have become antibiotic resistant due to antibiotics there is no evidence that recommended antiseptics or disinfectants selects for antibiotic-resistant organisms when used in hand washing. however, many strains of organisms are resistant to some of the substances used in antibacterial soaps such as triclosan. one survey of bar soaps in dentist clinics found they all had their own flora and on average from two to five different genera of microorganisms with those used most more likely to have more species varieties. another survey of bar soaps in public toilets found even more flora. another study found that very dry soaps are not infected while all are that rest in pools of water. however, research upon soap that was specially infected found that soap flora do not transmit to the hands. damaged skin washing skin repeatedly can damage the protective external layer and cause transepidermal loss of water. this can be seen in roughness characterized by scaling and dryness, itchiness, dermatitis provoked by microorganisms and allergens penetrating the corneal layer and redness. wearing gloves can cause further problems since it produces a humid environment favoring the growth of microbes and also contains irritants such as latex and talcum powder. hand washing can damage skin because the stratum corneum top layer of skin consists of 15 to 20 layers of keratin disks, corneocytes, each of which is each surrounded by a thin film of skin lipids which can be removed by alcohols and detergents. damaged skin defined by extensive cracking of skin surface, widespread reddening or occasional bleeding has also been found to be more frequently colonized by staphylococcus hominis and these were more likely to be methicillin resistant. though not related to greater antibiotic resistance, damaged skin was also more like to be colonized by staphylococcus aureus, gram-negative bacteria, enterococci and candida. comparison with other flora the skin flora is different from that of the gut which is predominantly bacillota and bacteroidota. there is also low level of variation between people that is not found in gut studies. both gut and skin flora however lack the diversity found in soil flora.