Bathing or showering cleans the skin by the mechanical removal of bacteria shed on corneocytes but the resident microflora are replenished immediately. Unclean individuals usually have higher microbial population densities on their skin. Personal hygienic habits influence the resident microflora.For example, young children have a more varied microflora and carry more gram-negative bacteria and potential pathogens than adults. Individual’s health, age, and gender determine the type and the density of skin flora.Īge-related changes in skin structure and function alter the microflora of the skin.Exposure to UV radiation kills the normal flora. Change in weather conditions and exposure to sunlight alters the temperature and humidity of the skin thus altering the number and diversity of skin microflora.Factors Affecting Skin FloraĪlthough the resident microflora on an individual’s skin remains relatively constant, various factors can affect the nature and extent of the normal flora: Malassezia spp., Aspergillus spp., Cryptococcus sp., Rhodotorula sp. Opportunistic fungal pathogen, Candida albicans is a member of the normal microflora of the skin. Yeasts are uncommon on the skin surface, but the lipophilic yeast Malassezia furfur is occasionally found on the scalp. coli, Klebsiella, Enterobacter, and Proteus. Predominant Gram-negative bacteria found on the skin are Acinetobacter, E. They are seen mostly in moist intertriginous areas, such as the toe webs and axilla. Gram-negative bacteria are minor constituents of the skin flora as they can’t compete with gram-positive organisms. It is ordinarily a harmless resident but certain strains can contribute to acne at puberty. Cutibacterium acnes (formerly Propionibacterium acnes) start colonizing after a child reaches the age of 10. These include Staphylococci, Micrococci, and a variety of both aerobic and anaerobic corynebacteria. Gram-positive bacteria are predominant members of the skin microbiome as they are better adapted to the dry conditions of the skin. To circumvent this problem, nowadays, sequencing methods ( 16S ribosomal RNA gene sequencing for bacteria) are used to enumerate skin microbiota. Traditionally, skin flora were identified by use of culture-based methods, which used to favor easily culturable organisms and fail to capture the complete diversity of the microbiome. The normal flora of the skin consists primarily of gram-positive bacteria. Resident microflora: Resident microorganisms are able to multiply, not merely survive, on the skin.Most of these organisms can’t multiply and ultimately die either because of low moisture content or low pH on the skin surface. Transient microflora: Skin is the largest and most exposed organ so it is continually being inoculated with microorganisms.The microorganisms of the normal flora of the skin are either transient or residents. When the balance is broken Types of Skin Flora.Underarm odor develops as a result of bacterial activity on the secretions of the apocrine glands. Sweat itself does not smell, bacteria on your skin are the culprits for your body odor. The distribution of sweat glands on skin surfaces and differences in the composition of their secretions also affect the nature of skin flora. ![]() Several kinds of sweat glands (such as eccrine glands, apocrine glands, and sebaceous glands) present in the skin secret secretions rich in microbial nutrients. Availability of nutrients is another major factor that alters the quantity and diversity of microflora in a particular niche. Residential microbial populations are higher in moist and warm areas of the skin such as axilla, perineum, and interdigital spaces of the toes. Someone has aptly compared it with geographic regions of the earth the desert of the forearm, the cool woods of the scalp, and the tropical forest of the armpit. subject to periodic drying but human skin is not uniform, it provides various micro-environments. Generally, the skin surface is not a favorable place for microbial growth, as it is dry, salty, and poor in nutrients. Skin surface varies greatly in chemical composition and moisture content. Schematic of skin histology viewed in cross-section with microorganisms and skin appendages (image source)
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