21.1 Anatomy and Normal Microbiota of the Skin and Eyes
5 min read•june 18, 2024
The skin and eyes are vital barriers against microbial invasion. Their unique structures and resident microbiomes work together to protect us from pathogens. The skin's layers and secretions, along with the 's tear film, create inhospitable environments for harmful microbes.
Despite these defenses, some microbes can bypass them through various mechanisms. Understanding how pathogens overcome our natural barriers is crucial for preventing and treating infections. Recognizing the signs of skin and eye infections helps in early diagnosis and intervention.
Anatomy and Normal Microbiota of the Skin and Eyes
Anatomical structures for microbial interactions
Top images from around the web for Anatomical structures for microbial interactions
Frontiers | The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems View original
Is this image relevant?
Frontiers | The Role of Skin and Orogenital Microbiota in Protective Immunity and Chronic Immune ... View original
Is this image relevant?
Frontiers | The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems View original
Is this image relevant?
Frontiers | The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems View original
Is this image relevant?
Frontiers | The Role of Skin and Orogenital Microbiota in Protective Immunity and Chronic Immune ... View original
Is this image relevant?
1 of 3
Top images from around the web for Anatomical structures for microbial interactions
Frontiers | The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems View original
Is this image relevant?
Frontiers | The Role of Skin and Orogenital Microbiota in Protective Immunity and Chronic Immune ... View original
Is this image relevant?
Frontiers | The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems View original
Is this image relevant?
Frontiers | The Skin and Intestinal Microbiota and Their Specific Innate Immune Systems View original
Is this image relevant?
Frontiers | The Role of Skin and Orogenital Microbiota in Protective Immunity and Chronic Immune ... View original
Is this image relevant?
1 of 3
- Skin
- outermost layer of skin provides physical barrier against microbes ()
- top layer of consists of dead and lipids (ceramides, cholesterol)
- Keratinocytes produce antimicrobial peptides (, ) and cytokines to combat pathogens
- antigen-presenting cells in the epidermis initiate immune responses to invading microbes
- layer beneath the epidermis contains connective tissue and immune cells
- produce extracellular matrix components (, ) that support skin structure
- Collagen and elastin fibers provide tensile strength and elasticity to the skin
- Blood vessels supply nutrients and oxygen to the skin and facilitate immune cell migration
- produce sweat that contains antimicrobial compounds (, )
- secrete that maintains skin moisture and has antimicrobial properties (free fatty acids, glycerol)
- provide a niche for specific microbes () and can serve as entry points for pathogens
- outermost layer of skin provides physical barrier against microbes ()
- Eyes
- thin mucous membrane that covers the white of the eye and inner eyelids
- transparent, avascular tissue that covers the front of the eye and provides a barrier against microbes
- Tear film lubricates and protects the surface of the eye
- Lipid layer outer layer of the tear film produced by the prevents tear evaporation
- Aqueous layer middle layer of the tear film produced by the lacrimal contains antimicrobial compounds (, , immunoglobulins)
- Mucin layer inner layer of the tear film produced by conjunctival goblet cells helps spread the tear film evenly over the eye surface
- Lacrimal glands produce that flush away microbes and contain antimicrobial compounds
- Meibomian glands secrete lipids that stabilize the tear film and have antimicrobial properties
Microbiomes of skin vs eyes
- Skin microbiome
- Varies based on skin region due to differences in production, moisture, and temperature
- Sebaceous sites (forehead, back) have higher proportions of lipophilic bacteria
- acnes predominant species in sebaceous areas thrives on sebum
- species (S. epidermidis, S. hominis) also abundant in sebaceous regions
- Moist sites (axilla, groin) favor the growth of bacteria that thrive in humid environments
- species (C. jeikeium, C. striatum) predominate in moist areas
- Staphylococcus species (S. hominis, S. haemolyticus) also present in moist regions
- Dry sites (forearm, palm) have a more diverse microbiome with lower bacterial density
- Proteobacteria (Acinetobacter, Pseudomonas) more abundant in dry areas
- (, ) also present in dry regions
- Sebaceous sites (forehead, back) have higher proportions of lipophilic bacteria
- Influenced by factors such as age (lower diversity in infants), gender (hormonal effects), and hygiene (handwashing, skincare products)
- contributes to skin health and protection against pathogens
- Varies based on skin region due to differences in production, moisture, and temperature
- Eye microbiome
- and tear film have a relatively stable and less diverse microbiome compared to the skin
- Coagulase-negative staphylococci (S. epidermidis) most abundant bacteria on the ocular surface
- Propionibacterium acnes also present in low numbers
- Corynebacterium species (C. macginleyi) commonly found on the conjunctiva
- species (S. mitis, S. oralis) part of the normal ocular flora
- and tear film have a relatively stable and less diverse microbiome compared to the skin
Microbial defense mechanisms and interactions
- plays a crucial role in protecting skin and eyes from pathogens
- on skin and eyes contribute to defense through
- , including the conjunctiva, have specialized defense mechanisms
- Some microbes can act as under certain conditions
Microbial defense bypass mechanisms
- Skin
- Penetration through breaks in the skin barrier allows microbes to access deeper tissues
- Wounds (cuts, scrapes) disrupt the and provide entry points for pathogens
- Abrasions (friction burns) remove the top layer of the epidermis, making the skin more susceptible to infection
- Insect bites (mosquitoes, ticks) can introduce pathogens directly into the
- Invasion via hair follicles and sweat glands allows bacteria to bypass the epidermis
- Production of enzymes to degrade skin components facilitates microbial invasion
- breaks down hyaluronic acid in the extracellular matrix, increasing tissue permeability
- Lipases degrade lipids in the stratum corneum, compromising the skin barrier
- Proteases (collagenases, elastases) degrade collagen and elastin fibers, weakening the skin structure
- Penetration through breaks in the skin barrier allows microbes to access deeper tissues
- Eyes
- Adherence to corneal or conjunctival epithelium allows bacteria to establish a foothold on the ocular surface
- Biofilm formation protects bacteria from antimicrobial agents and immune responses
- Evasion of tear film antimicrobial components enables microbes to survive on the eye surface
- enzymatically degrades bacterial cell walls
- Lactoferrin sequesters iron, limiting bacterial growth
- Immunoglobulins (IgA) neutralize microbes and prevent their attachment to the ocular surface
- Invasion through compromised corneal epithelium (due to injury or disease) allows microbes to access deeper layers of the eye
Signs of skin and eye infections
- Skin infections
- bacterial infection of the dermis and subcutaneous tissue
- Erythema (redness) due to increased blood flow to the infected area
- Warmth caused by inflammatory response
- Swelling (edema) resulting from increased vascular permeability
- Pain due to the release of inflammatory mediators and pressure on nerve endings
- superficial bacterial infection of the epidermis
- Honey-colored crusts formed by the accumulation of dried serum and bacteria
- Erythematous base (red, inflamed skin) surrounding the crusts
- infection of hair follicles
- (-filled bumps) or (solid bumps) centered on hair follicles
- bacterial infection of the dermis and subcutaneous tissue
- Eye infections
- inflammation of the conjunctiva
- Redness due to dilation of conjunctival blood vessels
- Discharge ( or watery) caused by increased mucus production and inflammatory exudate
- Itching or burning sensation resulting from the release of inflammatory mediators
- infection or inflammation of the cornea
- Corneal opacity (clouding) due to inflammatory infiltrates and edema
- Pain caused by the exposure of corneal nerves
- Photophobia (light sensitivity) due to corneal irritation
- Decreased visual acuity resulting from corneal opacity and irregular surface
- inflammation of the eyelid margins
- Eyelid inflammation (redness, swelling) due to the accumulation of bacteria and debris
- Crusting or flaking of eyelid margins caused by the buildup of oils, dead skin cells, and bacteria
- inflammation of the conjunctiva
Key Terms to Review (107)
Abscess: An abscess is a confined pocket of pus that collects in tissues, organs, or spaces inside the body, usually caused by a bacterial infection. It forms as a defensive reaction of tissue to prevent the spread of infectious materials to other parts of the body.
Adenovirus: Adenovirus is a type of DNA virus that commonly causes respiratory, eye, and gastrointestinal infections. It is also used as a vector in gene therapy due to its ability to deliver genes to host cells.
Barrier Function: Barrier function refers to the ability of the skin and eyes to act as a protective barrier against external threats, such as pathogens, chemicals, and physical damage. This function is crucial in maintaining the body's homeostasis and preventing the entry of harmful agents into the body.
Betaproteobacteria: Betaproteobacteria are a class of Gram-negative bacteria within the phylum Proteobacteria, characterized by their metabolic diversity. They play significant roles in nitrogen fixation and are commonly found in soil and water environments.
Blepharitis: Blepharitis is an inflammation of the eyelid margins, often involving bacterial infection or skin conditions. It typically presents with redness, itching, and crusting around the eyelashes.
Blepharitis: Blepharitis is a common inflammatory condition affecting the eyelids, often involving the oil glands located along the edge of the eyelids. It can lead to redness, irritation, and discomfort in the eyes and eyelids.
Boil: A boil, also known as a furuncle, is a painful, pus-filled infection of a hair follicle caused primarily by Staphylococcus aureus bacteria. Boils are characterized by redness, swelling, and the accumulation of pus.
Bulla: A bulla is a large, fluid-filled blister that forms on the skin due to various causes including infections and trauma. It is typically greater than 0.5 cm in diameter.
Bullae: Bullae are large, fluid-filled blisters that form on the skin due to various infections or conditions. They are typically larger than 0.5 cm in diameter and can be caused by bacterial infections such as Staphylococcus aureus.
Carbuncle: A carbuncle is a cluster of connected furuncles (boils) caused by bacterial infection, typically Staphylococcus aureus. It results in deep skin abscesses that can lead to severe pain and systemic symptoms.
Cathelicidins: Cathelicidins are a family of antimicrobial peptides that serve as important chemical defenses against pathogens. They play a crucial role in the innate immune system's pathogen recognition and phagocytosis processes, as well as in maintaining the normal microbiota of the skin and eyes.
Cellulitis: Cellulitis is a bacterial infection of the skin and subcutaneous tissues characterized by redness, swelling, warmth, and pain. It commonly affects the lower legs but can occur anywhere on the body.
Cellulitis: Cellulitis is a potentially serious bacterial skin infection that typically occurs when bacteria, often Streptococcus or Staphylococcus, enter the skin through a cut, scratch, or other break in the skin. It can cause redness, swelling, warmth, and pain in the affected area, and if left untreated, can spread to the bloodstream and other tissues.
This term is particularly relevant to the topics of 21.1 Anatomy and Normal Microbiota of the Skin and Eyes, 21.2 Bacterial Infections of the Skin and Eyes, and 25.1 Anatomy of the Circulatory and Lymphatic Systems, as cellulitis involves the skin, eyes, and can spread through the circulatory and lymphatic systems.
Chryseobacterium: Chryseobacterium is a genus of Gram-negative, aerobic, non-spore-forming bacteria that are commonly found in the environment, including the normal microbiota of the skin and eyes. These bacteria are known for their ability to produce yellow-pigmented colonies and their potential to cause opportunistic infections in humans.
Circoviridae: Circoviridae is a family of small, non-enveloped viruses with circular single-stranded DNA genomes. They are known to infect both animals and plants, causing various diseases.
Collagen: Collagen is the most abundant protein in the human body, found primarily in the skin, eyes, and connective tissues. It is a structural protein that provides strength, elasticity, and support to various body structures.
Conjunctiva: The conjunctiva is a thin, transparent membrane that covers the white part of the eye (sclera) and lines the inside of the eyelids. It helps protect the eye by producing mucus and tears to keep it moist.
Conjunctiva: The conjunctiva is a thin, transparent membrane that lines the inner surface of the eyelids and covers the front part of the eye, known as the sclera. It plays a crucial role in the anatomy and normal microbiota of the skin and eyes.
Conjunctivitis: Conjunctivitis, commonly known as pink eye, is an inflammation or infection of the conjunctiva, the transparent membrane that lines your eyelid and covers the white part of your eyeball. It can be caused by bacteria, viruses, allergens, or irritants.
Conjunctivitis: Conjunctivitis is an inflammation or infection of the conjunctiva, the transparent membrane that covers the white part of the eye and the inner surface of the eyelids. It can be caused by various factors, including bacterial or viral infections, allergies, and irritants, and is commonly known as 'pink eye.'
Contact lenses: Contact lenses are thin, curved lenses placed directly on the surface of the eyes to correct vision or for cosmetic reasons. They can create a favorable environment for microbial growth if not properly maintained.
Cornea: The cornea is the transparent, curved, outermost layer of the eye that helps focus light into the eye. It is the eye's first and most powerful lens, refracting light to allow clear vision.
Corynebacterium: Corynebacterium is a genus of Gram-positive, non-spore-forming, rod-shaped bacteria that are commonly found as part of the normal microbiota in various regions of the human body, including the skin, respiratory tract, and urogenital tract.
Crust: A crust is a hardened layer of dried blood, plasma, or exudate on the skin's surface, often forming over a wound or infection site. It serves as a protective barrier during the healing process.
Cyst: A cyst is a dormant, resistant form of a unicellular eukaryotic organism that helps it survive harsh conditions. Cysts are often part of the life cycle of parasitic protozoa and can be involved in transmission to new hosts.
Dacrocyst: A dacrocyst is the lacrimal sac, which is part of the tear drainage system situated between the inner corner of the eye and the nasal cavity. It plays a crucial role in draining tears from the eye into the nasal passage.
Dacryocystitis: Dacryocystitis is an infection of the lacrimal sac, usually caused by a blockage in the nasolacrimal duct. It leads to pain, redness, and swelling in the inner corner of the eye.
Defensins: Defensins are small, antimicrobial peptides produced by various cells, including epithelial cells and neutrophils. They play a crucial role in the innate immune system by disrupting the membranes of pathogens.
Defensins: Defensins are a class of antimicrobial peptides that serve as part of the innate immune system's chemical defenses against pathogens. They are found in various tissues and bodily fluids, playing crucial roles in pathogen recognition, phagocytosis, and protecting the integrity of the skin, eyes, respiratory tract, and oral cavity.
Dermcidin: Dermcidin is an antimicrobial peptide produced by eccrine sweat glands in the skin. It plays a crucial role in the skin's innate immune defense system, providing protection against various pathogens that may threaten the body's largest organ.
Dermis: The dermis is the middle layer of the skin located beneath the epidermis. It contains connective tissue, blood vessels, nerve endings, sweat glands, and hair follicles.
Dermis: The dermis is the thick, inner layer of the skin that lies beneath the epidermis. It is responsible for providing structural support, nourishment, and protection to the skin, as well as playing a crucial role in the normal microbiota of the skin and eyes.
Desquamation: Desquamation is the shedding or peeling of the outermost layer of the skin, known as the stratum corneum. This process plays a crucial role in maintaining healthy skin by removing dead cells and allowing for regeneration.
Elastin: Elastin is a highly elastic protein found in the extracellular matrix of various connective tissues, such as the skin, blood vessels, and lungs. It provides the ability for these tissues to stretch and recoil, allowing for flexibility and resilience.
Elizabethkingia: Elizabethkingia is a genus of Gram-negative, non-spore-forming, non-motile, aerobic bacteria that are commonly found in the environment, including soil, water, and the skin microbiota. This genus is named after Elizabeth O. King, the microbiologist who first identified and characterized these bacteria.
Epidermis: The epidermis is the outermost layer of the skin, serving as a protective barrier against environmental threats and pathogens. It is composed primarily of keratinocytes and lacks blood vessels.
Epidermis: The epidermis is the outermost layer of the skin, serving as a protective barrier against environmental threats and preventing water loss from the body. It is a crucial component of the skin's anatomy and plays a vital role in the normal microbiota and viral infections affecting the skin and eyes.
Eye: The eye is a complex sensory organ responsible for vision, composed of various structures including the cornea, lens, retina, and optic nerve. It is also susceptible to infections caused by various microorganisms.
Fibroblasts: Fibroblasts are a type of connective tissue cell that play a crucial role in the structure and function of the skin and eyes. These cells are responsible for the production of the extracellular matrix, which provides the framework and support for various tissues in the body.
Flavobacteriales: Flavobacteriales is an order of Gram-negative bacteria that are commonly found in the normal microbiota of the skin and eyes. These bacteria are known for their distinctive yellow pigmentation and their ability to degrade a variety of organic compounds, making them important players in the ecosystem of the human body's integumentary and visual systems.
Folliculitis: Folliculitis is an inflammation of the hair follicles commonly caused by bacterial infection, particularly Staphylococcus aureus. It often manifests as red, swollen, and pus-filled bumps on the skin.
Folliculitis: Folliculitis is a common skin condition characterized by inflammation of the hair follicles, often resulting in small, red, and sometimes pus-filled bumps on the skin. It can occur in various parts of the body, particularly areas with a high density of hair follicles.
Furuncle: A furuncle, also known as a boil, is a painful, pus-filled bump under the skin caused by bacterial infection, typically Staphylococcus aureus. They develop when bacteria infect hair follicles or oil glands.
Glands: Glands are specialized organs that secrete substances necessary for various bodily functions. In the skin, glands play a crucial role in maintaining homeostasis and protecting against infections.
Hair follicles: Hair follicles are tubular structures in the skin from which hair grows. They play a crucial role in housing and protecting various microorganisms that form part of the skin's normal microbiota.
Hyaluronidase: Hyaluronidase is an enzyme that breaks down hyaluronic acid, a key component of the extracellular matrix in the skin and eyes. It plays a crucial role in the anatomy and normal microbiota of these tissues.
Hypodermis: The hypodermis, also known as the subcutaneous layer, is the deepest layer of skin that lies below the dermis. It primarily consists of fat and connective tissues that provide insulation and cushioning for the body.
Impetigo: Impetigo is a highly contagious bacterial skin infection caused by Staphylococcus or Streptococcus bacteria. It is characterized by the development of red sores, blisters, and crusty lesions, typically on the face, hands, and other exposed areas of the body.
Innate Immunity: Innate immunity refers to the body's natural, non-specific defense mechanisms that provide immediate protection against pathogens. It is the first line of defense against infectious agents and plays a crucial role in maintaining overall immune function.
Keratin: Keratin is a fibrous structural protein found in the outer layer of the skin, as well as in hair and nails. It provides protection and strength to epithelial cells against damage or stress.
Keratinocytes: Keratinocytes are the predominant cell type in the epidermis, the outermost layer of the skin. They are responsible for the production of keratin, a structural protein that provides strength and protection to the skin.
Keratitis: Keratitis is the inflammation of the cornea, often caused by infections or injury. It can lead to pain, impaired vision, and if untreated, blindness.
Keratitis: Keratitis is an inflammation of the cornea, the transparent, dome-shaped structure at the front of the eye. It can be caused by various factors, including bacterial infections, viral infections, fungal infections, trauma, or underlying medical conditions, and can lead to vision problems if left untreated.
Keratoconjunctivitis: Keratoconjunctivitis is an inflammation of both the cornea and conjunctiva, typically caused by infections, allergens, or irritants. It can result in symptoms such as redness, pain, and visual disturbances.
Lacrimal ducts: Lacrimal ducts are small channels located in the inner corner of the eyelids that drain tears from the eye's surface into the nasal cavity. They play a crucial role in maintaining eye health by facilitating tear drainage and preventing microbial infections.
Lacrimal gland: The lacrimal gland is a small, almond-shaped gland located in the upper outer region of the orbit that produces tears. It plays a crucial role in lubricating and protecting the surface of the eye.
Lacrimal punctum: The lacrimal punctum is a small opening on the inner corner of the eyelids that drains tears from the surface of the eye into the nasal cavity. It plays a crucial role in tear drainage and maintaining ocular surface health.
Lacrimal sac: The lacrimal sac is a part of the tear drainage system located in the medial aspect of each eye socket. It collects tears from the eyes and drains them into the nasolacrimal duct.
Lactoferrin: Lactoferrin is a multifunctional glycoprotein found in various secretory fluids, such as milk, saliva, and tears. It plays a crucial role in the body's innate immune system by binding iron and exhibiting antimicrobial properties.
Lactoferrin: Lactoferrin is an iron-binding glycoprotein found in various exocrine secretions, such as tears, saliva, and nasal and bronchial mucus, as well as in milk. It plays a crucial role in the innate immune system and the maintenance of healthy skin and eye microbiota.
Langerhans Cells: Langerhans cells are a type of dendritic cell found in the epidermis, the outermost layer of the skin. They play a crucial role in the skin's immune defense system and are considered part of the physical defenses against pathogens.
Lesions: Lesions are areas of abnormal tissue on the skin or eyes, often caused by infection, trauma, or disease. They can vary in appearance and may include ulcers, sores, or rashes.
Lysozyme: Lysozyme is an enzyme that breaks down the cell walls of bacteria, particularly Gram-positive bacteria, by cleaving the bonds in peptidoglycan. It is a crucial component of the innate immune system and is found in various body fluids such as tears, saliva, and mucus.
Lysozyme: Lysozyme is an enzyme found in various body fluids, such as tears, saliva, and mucus, that acts as a natural antimicrobial agent by breaking down the cell walls of certain bacteria. It is an important component of the body's innate immune system, providing a physical and chemical defense against pathogens.
Macules: Macules are flat, distinct, discolored areas of skin less than 1 centimeter wide without any change in texture or thickness. They are often a sign of underlying infections or conditions affecting the skin.
Meibomian Glands: Meibomian glands are specialized sebaceous glands located within the eyelids that produce an oily substance called meibum. This oily secretion is an essential component of the tear film, helping to prevent tear evaporation and maintain eye health.
Microbial Antagonism: Microbial antagonism refers to the inhibition or suppression of the growth and activities of one microorganism by another, often through the production of antimicrobial substances or the competition for resources. This concept is particularly relevant in the context of the anatomy and normal microbiota of the skin and eyes, where various microbial species coexist and interact.
Microbiome Diversity: Microbiome diversity refers to the variety and richness of microbial communities that inhabit different parts of the human body, such as the skin and eyes. It encompasses the abundance and distribution of various microorganisms, including bacteria, archaea, fungi, and viruses, that coexist in a delicate balance and contribute to overall health and well-being.
MRSA: MRSA (Methicillin-resistant Staphylococcus aureus) is a type of Gram-positive bacterium that is resistant to several widely used antibiotics, making it difficult to treat. It commonly causes skin and soft tissue infections but can lead to more severe invasive diseases.
Mucins: Mucins are high molecular weight glycoproteins produced by epithelial tissues, serving as a protective barrier on mucosal surfaces. They play a crucial role in lubrication, cell signaling, and pathogen defense.
Mucosal Surfaces: Mucosal surfaces refer to the moist, protective linings found in various parts of the body, such as the respiratory, digestive, and urinary tracts. These surfaces act as a barrier against pathogens and provide a habitat for the normal microbiota, playing a crucial role in maintaining overall health.
Nasolacrimal duct: The nasolacrimal duct is a tubular structure that connects the lacrimal sac to the nasal cavity, facilitating the drainage of tears from the eye surface into the nose. It plays a crucial role in tear drainage and maintaining eye health.
Opportunistic pathogens: Opportunistic pathogens are microorganisms that cause disease primarily in hosts with weakened immune systems. They typically do not cause illness in healthy individuals with intact immune defenses.
Opportunistic Pathogens: Opportunistic pathogens are microorganisms that typically do not cause disease in healthy individuals, but can take advantage of a compromised immune system or a disruption in the normal microbiota to cause infection. These pathogens become a concern in the context of the skin, eyes, and other body sites where the normal microbiota plays a critical role in maintaining health.
Papillomaviridae: Papillomaviridae is a family of non-enveloped, double-stranded DNA viruses known to cause papillomas (warts) in humans and animals. These viruses are capable of infecting skin and mucous membranes.
Papules: Papules are small, raised, solid pimples or swellings on the skin that do not contain pus. They are often caused by inflammation or infection and can be a sign of various skin conditions.
Picornaviradae: Picornaviridae is a family of small, non-enveloped RNA viruses that includes pathogens causing various human and animal diseases. These viruses have an icosahedral capsid and are known for their stability in the environment.
Pinkeye: Pinkeye, or conjunctivitis, is an inflammation of the conjunctiva caused by bacterial, viral, or allergic agents. It results in redness, swelling, and discharge from the eye.
Polyomaviridae: Polyomaviridae is a family of small, non-enveloped DNA viruses known to infect mammals and birds. Some members of this family can cause skin and eye infections in humans.
Propionibacteria: Propionibacteria are a group of Gram-positive anaerobic bacteria commonly found on human skin. They play a significant role in the development of acne and other skin conditions.
Propionibacterium: Propionibacterium is a genus of anaerobic, gram-positive bacteria that are commonly found as part of the normal microbiota of the skin and eyes. These bacteria play a crucial role in the anatomy and physiology of these body sites.
Propionibacterium acnes: Propionibacterium acnes is an anaerobic, gram-positive bacterium that is a common inhabitant of the human skin and is associated with the development of acne. It plays a significant role in the normal microbiota of the skin and eyes, as well as in bacterial infections affecting these areas.
Pseudocyst: A pseudocyst is a fluid-filled cavity that lacks an epithelial lining and often forms in response to infection or trauma. It can occur in various tissues, including the skin.
Purulent: Purulent describes a condition characterized by the presence of pus, which is a thick fluid composed of white blood cells, dead tissue, and bacteria. It commonly indicates an infection.
Pus: Pus is a thick fluid composed of white blood cells, dead tissue, and bacteria, typically resulting from an infection. It is a sign of the body's immune response to fight off pathogens.
Pustules: Pustules are small, inflamed, pus-filled lesions on the skin that typically result from bacterial infections. They are often associated with conditions like acne and impetigo.
Pyoderma: Pyoderma is a bacterial skin infection characterized by the presence of pus. It commonly results from the invasion of bacteria into hair follicles, sweat glands, or broken skin.
Rashes: Rashes are visible changes in the texture or color of the skin that often manifest as red, inflamed patches. They can be caused by infections, allergies, or other underlying health conditions.
Resident Flora: Resident flora refers to the microorganisms that permanently reside on or within the human body, forming a stable and symbiotic relationship with the host. These microorganisms, primarily bacteria, play a crucial role in maintaining the health and homeostasis of the skin, eyes, and other body surfaces.
Sebaceous glands: Sebaceous glands are small oil-producing glands present in the skin. They secrete sebum, which lubricates and waterproofs the skin and hair.
Sebaceous Glands: Sebaceous glands are specialized exocrine glands found in the skin that produce an oily substance called sebum. These glands play a crucial role in the skin's physical defenses and the normal microbiota of the skin and eyes.
Sebum: Sebum is an oily substance produced by sebaceous glands in the skin. It plays a role in maintaining skin hydration and providing a barrier against microbial invasion.
Sebum: Sebum is an oily, waxy substance produced by the sebaceous glands in the skin. It plays a crucial role in the physical defenses of the skin and the normal microbiota of the skin and eyes.
Staphylococcus: Staphylococcus is a genus of Gram-positive bacteria known for their spherical shape and tendency to form clusters resembling grapes. They are commonly found on the skin and in the nasal passages of humans.
Staphylococcus epidermidis: Staphylococcus epidermidis is a Gram-positive, coagulase-negative bacterium that is a common member of the normal human skin and mucous membrane microbiota. It is considered an opportunistic pathogen, capable of causing infections in immunocompromised individuals or when the skin barrier is breached.
Stratum corneum: The stratum corneum is the outermost layer of the epidermis, composed mainly of dead keratinized cells. It acts as a barrier to protect underlying tissues from infection, dehydration, and physical harm.
Stratum Corneum: The stratum corneum is the outermost layer of the epidermis, the skin's protective barrier. It is a crucial component of the physical defenses of the body and plays a key role in the anatomy and normal microbiota of the skin and eyes.
Streptococcus: Streptococcus is a genus of Gram-positive bacteria that often occur in chains or pairs. They are known for causing a variety of infections in humans, ranging from mild throat infections to life-threatening diseases.
Suppurative: Suppurative refers to the production or discharge of pus, commonly in response to bacterial infection. It is a characteristic feature of many skin and eye infections.
Sweat glands: Sweat glands are small tubular structures in the skin responsible for producing sweat. They play a crucial role in thermoregulation and excretion.
Tear sac: The tear sac, or lacrimal sac, is part of the tear drainage system in the eye. It collects tears from the eye and drains them into the nasal cavity.
Tears: Tears are a liquid secretion produced by the lacrimal glands to lubricate the eyes and provide immune defense. They contain enzymes and antimicrobial proteins that protect against pathogens.
Ulcer: An ulcer is an open sore or lesion that fails to heal, often caused by infection, underlying medical conditions, or physical trauma. Ulcers can occur on the skin or mucous membranes of the digestive system.
Vesicle: A vesicle is a small, membrane-bound sac within cells that transports substances. Vesicles play critical roles in processes such as transport of lipids and proteins, and in cellular communication.
Viromes: Viromes are the collections of viruses present in a particular environment, including the human skin and eyes. They play roles in health and disease by interacting with other microbes and host cells.
Vitreous humor: The vitreous humor is a clear, gel-like substance that fills the space between the lens and the retina of the eye. It helps maintain the eye's shape and optical properties.
Wheal: A wheal is a raised, itchy area of skin that is often a sign of an allergic reaction or infection. It typically resolves within a few hours to days.