The microorganisms known as normal flora are those that coexist in our bodies in a generally steady way without having an adverse impact on the host's health. These microorganisms—bacteria and fungi—colonize the skin and mucous membranes permanently or for a brief time throughout life.
Normal Flora of Skin, Hair, and Nail
The skin is our body's outermost layer of protection. Ironically, it serves as both our body's defence against foreign microbes and a haven for a diverse range of bacteria and fungus. Skin is filled with typical microfloras that, when disturbed by washing or other physical activity, reestablish themselves. Dryness of the skin, pH, salt concentration, oiliness, and direct contact to the environment (clothing habit) all have an impact on the skin flora. More variety may be found in moist locations such the perianal region, groyne regions, face, inner thigh section, and scalp. In such damp locations, Gram-positive and Gram-negative bacteria are more prevalent. Gram-positive bacteria, which are rather rare, predominate in the remaining dry sections. Additionally, body hair has a rich surface flora of bacteria and fungi. Compared to other body parts, the nail has a higher concentration of fungi.
Table of Contents
- List of Normal Flora of Skin, Hair, and Nail
- Gram +ve and Gram -ve Bacteria of Skin, Hair, and Nail
- Staphylococcus spp.
- Streptococcus spp.
- Micrococcus spp.
- Corynebacterium spp.
- Propionibacterium spp.
- Bacillus spp.
- Aerococcus spp.
- Enterobacter spp.
- Klebsiella spp.
- E. coli
- Proteus spp.
- Pseudomonas spp.
- Acinetobacter spp.
- Fungi Microbiome of Skin, Hair, and Nail
List of Normal Flora of Skin, Hair, and Nail
|
Gram-Positive Bacteria |
Gram-Negative Bacteria |
Fungi |
|
Staphylococcus spp. |
Enterobacter spp. |
Candida spp. |
Gram +ve and Gram -ve Bacteria of Skin, Hair, and Nail
Staphylococcus spp.
- Gram-positive
- Catalase-positive
- Coagulase positive and coagulase-negative
- Aerobic
- Cocci bacteria
- Family – Staphylococcaceae
- Seen in a grape-like cluster under a microscope
On human skin, Staphylococcus is the predominant species. It may be found in hair and nails as well as the skin on the scalp, arms, torso, legs, and groyne. They are the natural flora that lives on human skin, and when they are disturbed, they swiftly reestablish.
The predominant species on human skin is S. epidermidis. It encompasses more than 90% of the local flora population in certain regions.
Another typical species found in the scalp, nose, perineum, vulvar skin, and hair follicles is S. aureus. They make from 10 to 40 percent of an adult person.
The skin of a healthy person contains S. hominis, S. haemolyticus, S. warneri, and S. capitis, among other common Staphylococcus species.
Streptococcus spp.
- Gram-positive
- Anaerobic and facultative anaerobic
- Catalase-negative
- Cocci bacteria
- Family – Streptococcaceae
- Seen in a form of a chain of spheres under a microscope
Hemolytic streptococci are mostly present on human skin as commensals. Moreover, commensals of hemolytic species are only sometimes discovered in humans. Viridans streptococci are found in the mouth area, groyne region, and perineum. They are usually ephemeral plants.
Micrococcus spp.
- Gram-positive
- Mostly non-motile (few species are motile)
- Strictly aerobic
- Cocci in clusters
- Family – Micrococcaceae
In addition, Micrococcus is widely distributed in most people's skin. They make about 20% of the bacteria that are found on the scalp, arms, and leg skin. Around 20 to 80% of cutaneous micrococci are dominated by the species M. luteus.
Corynebacterium spp.
- Gram-positive
- Rod-shaped (club-shaped),
- Aerobic bacteria
- Family – Corynebacteriaceae
Characteristic elevated levels of meso-Diaminopimelic acid and arabinogalactan repetition
In large amounts, Corynebacterium can be found on wet skin. Anaerobic Corynebacteria are widely distributed in areas with a high density of sebaceous glands. Some of the most common Corynebacteria found in human skin include C. parvum, C. xerosis, C. jeikeium, and C. minutissimum.
Propionibacterium spp.
- Gram-positive
- Rod-shaped
- Anaerobic
- Family – Propionibacteriaceae
Unusual capacity to create propionic acid utilising transcarboxylase enzymes
One of the most often identified bacteria from adult skin is propionibacterium. Children under 10 are seldom found to have these bacteria. When a person enters puberty, skin colonisation starts. On human skin, P. granulosum, P. avidum, and P. acne are the most prevalent species.
Bacillus spp.
- Gram-positive
- Rod-shaped
- Motile
- Obligate aerobic and some facultative anaerobic
- Spore forming
- Family – Bacillaceae
Both the dry and the wet parts of the skin contain Bacillus species. They only cover a tiny fraction of the skin flora, though.
Aerococcus spp.
- Gram-positive
- Catalase-negative
- Cocci
- Aerobic
- Family – Aerococcaceae
The typical flora of the skin is A. viridans.
Enterobacter spp.
- Gram-negative
- Rod-shaped
- Motile
- Lactose fermenting
- Facultatively anaerobic
- Mesophillic coliform bacteria
- Family – Enterobacteriaceae
In wet environments, primarily the perianal region, Enterobacter spp. are prevalent. Most people are familiar with E. cloacae.
Klebsiella spp.
- Gram-negative
- Rod-shaped
- Non-motile
- Encapsulated
- Lactose fermenting
- Facultatively anaerobic
- Mesophillic coliform bacteria
- Family – Enterobacteriaceae
The skin of the vagina, the perianal region, and the groynes contain Klebsiella spp. They usually consist of migratory flora that originated in the rectum.
E. coli
- Gram-negative
- Rod-shaped
- Motile
- Lactose fermenting
- Facultatively anaerobic
- Mesophilic coliform bacteria
- Family – Enterobacteriaceae
- Genus – Escherichia
E. coli may be found in wet locations such the perineum, perianal region, and moist intertriginous areas.
Proteus spp.
- Gram-negative
- Rod-shaped
- Aerobic and facultative anaerobic
- Motile bacteria
- Family – Enterobacteriaceae
Pseudomonas spp.
- Gram-negative
- Rod-shaped
- Aerobic
- Gammaproteobacteria
- Family – Pseudomonadaceae
Rarely isolated, P. aeruginosa is a common resident of human skin.
Acinetobacter spp.
- Gram-negative
- Oxidase-negative
- Nonfermentive
- Strictly aerobic
- Bacilli (or coccobacilli)
- Gammaproteobacteria
- Family – Moraxellaceae
Moist skin contains acinetobacter. The species A. lwoffii and A. johnsonii are frequent in wet skin.
Fungi Microbiome of Skin, Hair, and Nail
Candida spp.
A genus of yeast in the Saccharomycetaceae family is called Candida. They are actual yeasts with the ability to form pseudohyphae. They are a typical resident of the moist skin of the groyne, perianal region, perineum, and vaginal skin. In moist skin, C. albicans and C. parapsilosis are the most prevalent species.
Epidermophyton spp.
A genus of filamentous fungus belonging to the Ascomycota class is called Epidermophyton. They are opportunistic microorganisms that cause cutaneous and superficial mycoses. They naturally live on human skin, primarily in the toe and foot nails. The main transitory flora in this genus is E. floccosum.
Aspergillus spp.
A genus of filamentous fungus belonging to the Ascomycota order is called Aspergillus. They are present in the dry skin and nails as temporary flora, but they can infect people. They are the most prevalent species of filamentous fungi found in human skin, hair, and nails. Common species that may be found isolated from the nail and skin are A. fumigatus, A. flavus, and A. versicolor.
Penicillium spp.
A genus of filamentous fungus belonging to the Ascomycota class is called Penicillium. They are typical flora in dry skin and nails. They are ephemeral plants that penetrate the body from the outside.
Cladosporium spp.
A genus of filamentous fungus belonging to the Ascomycota class is called Cladosporium. They are sporadic species of dry skin and nail flora.
Mucor spp.
A genus of filamentous fungus belonging to the class Mucoromycota is called Mucor. Under the nail, Mucor is a common isolation of a fungus.
Rhodotorula spp.
A genus of coloured yeasts in the class Basidiomycota is called Rhodotorula. They are a kind of yeast that may be found in wet skin and nails.
Malassezia spp.
A genus of yeasts in the class Basidiomycota is called Malassezia. The most prevalent fungus genus found in most people is Malassezia. In the scalp, hair follicles, intertriginous regions, nails, and moist skin, they are the typical flora of human skin. The most prevalent species are M. globosa, M. ovale, and M. furfur.
~1.webp)
