Chapter 21: Skin and Eye Infections

acanthamoeba keratitis

acanthamoeba keratitis

can cause keratitis (corneal inflammation) and blindness; a serious infection that affects the cornea It’s caused by an amoeba which enters your eye and eats through the layers of your cornea

acne

result from inflammation of hair follicles; a bacterial infection of the skin that manifests as a rash of inflamed hair follicles (folliculitis).

anthrax

an infection caused by the spore-forming bacteria called Bacillus anthracis. It is a zoonosis (disease transmissible from animals to humans) that typically affects animals; found in soil

blepharitis

an inflammation of the eyelids

carbuncles

is a skin infection that is characterized by a cluster of boils that are connected to each other under the skin; the boils are usually red, swollen, painful, and pus-filled; can spread through skin to skin contact or sharing items; “multiple furuncles”

cellulitis

a bacterial skin infection in dermis or hypodermis that can cause redness, swelling, and pain in the affected area. usually caused by bacteria such as streptococcus or staphylococcus that enter the body through a cut, scrape, or other break in the skin; the affected skin may also feel warm to the touch and may develop blisters or dimpling

comedones

a type of acne that is characterized by small bumps on the skin; they are caused by clogged hair follicles and can appear as either blackheads or whiteheads

conjunctiva

the mucous membrane that covers the front of the eye and lines the inside of the eyelids; responsible for producing mucous and tears that protect and lubricate the eye

conjunctivitis

also known as “pink eye”; an inflammation of the transparent membrane that lines the eyelid and eyeball; small blood vessels in the conjunctiva become swollen and irritated causing the eye to become reddish pink

cornea

the transparent layer forming the front of the eye; covers pupil, iris, and anterior chamber

cutaneous aspergillosis

a type of infection caused by the fungus aspergillius; enters the body through a break in the skin, such as a wound or burn; symptoms include skin lesions that can be painful and contain pus; result in distinctive eschars that form at the site or sites of infection

cutaneous candidiasis

a fungal yeast infection of the skin caused by an overgrowth of candida; causes a red, itchy rash to form, most commonly in the folds of the skin

dermatophytes

pathogenic fungi capable of causing skin infections such as athlete’s foot, jock itch, and ringworm

dermis

the middle layer of the skin, located between the epidermis and hypodermis; composed of connective tissue and contains blood vessels, nerves, hair follicles, sweat glands, and sebaceous glands; plays a crucial role in regulating body temperature and sensation.

desquamation

shedding and peeling of skin

epidermis

the outermost layer of the skin.; acts as a protective barrier against external factors and helps regulate body temperature; composed of multiple layers of cells, including keratinocytes, which produce the protein keratin

erysipelas

a condition that presents as a large, intensely inflamed patch of skin involving the dermis (often on the legs or face); treatment is commonly penicillin

erythema

superficial reddening of the skin, usually in patches, as a result of injury or irritation causing dilatation of the blood capillaries

erythema nodosum

inflammation in the subcutaneous fat cells of the hypodermis; it sometimes results from a streptococcal infection, though other pathogens can also cause the condition; it is not suppurative, but leads to red nodules on the skin, most frequently on the shins

eschar

dead tissue that falls of healthy tissue; particularly after a burn injury; contains necrotic tissue and is black or dark brown in color

fifth disease

another common, highly contagious illness that causes a distinct rash that is critical to diagnosis. It is caused by parvovirus B19, and is transmitted by contact with respiratory secretions from an infected individual. Infection is more common in children than adults. While approximately 20% of individuals will be asymptomatic during infection, others will exhibit cold-like symptoms (headache, fever, and upset stomach) during the early stages when the illness is most infectious

folliculitis

a common skin condition characterized by inflammation of hair follicles; can be caused by bacterial, fungal, or viral infections, as well as other factors like friction or shaving; symptoms include redness, swelling, and pustules around the hair follicles; treatment options include topical or oral antibiotics, antifungal medications, and proper hygiene practices

furuncles

also known as boils, are painful skin infections caused by bacteria; they typically start as a red, tender lump that gradually fills with pus; treatment usually involves applying warm compresses to the affected area and, in some cases, antibiotics may be prescribed

hair follicles

small, tube-like structures in the skin that produce and grow hair; found all over the body, except for the palms of the hands and the soles of the feet

herpes keratitis

a viral infection of the eye; HSV-1 and deep lesions form and could lead to blindness; antiviral treatment is required

hypodermis

the innermost layer of the skin, located beneath the dermis; composed of adipose tissue and connective tissue; helps to insulate the body, store energy, and provide cushioning and protection to underlying structures.

impetigo

skin infection that causes the formation of vesicles, pustules, and possibly bullae, often around the nose and mouth; can be diagnosed as either nonbullous or bullous.

intertrigo

a general term for a rash that occurs in a skin fold, or other localized rashes on the skin; Candida spp. are sometimes responsible for this

keratin

a fibrous structural protein found in the outer layer of the skin, hair, nails, and other epithelial cells; provides strength and protection to these tissues; responsible for the structural integrity and waterproofing properties of the skin and hair

keratitis

an inflammation of the cornea

keratoconjunctivitis

an inflammation of both the cornea and the conjunctiva

lacrimal ducts

small channels that drain tears from the surface of the eye into the nasal cavity; helps to keep the eyes moist and remove any excess tears

lacrimal gland

a gland located above the outer corner of each eye that produces tears

lacrimal punctum

a small opening located on the inner corner of the eyelid; serves as the entry point for tears into the lacrimal drainage system.

lacrimal sac

a structure located in the upper outer corner of the eye socket; part of the lacrimal system; collects tears from the surface of the eye and then drains them into the nasolacrimal duct, which leads to the nasal cavity

M protein

a structural protein found in certain viruses, such as the influenza virus; plays a crucial role in the viral life cycle by helping the virus attach to and enter host cells; is involved in the assembly and release of new viral particles

macule

a non-elevated spot on the skin that is discolored from the surrounding skin and is less than 1cm wide

nasolacrimal duct

a passage that allows tears to drain from the eyes into the nasal cavity; starts at the inner corner of the eye and extends down to the nasal cavity, helping to keep the eyes moist and preventing tears from overflowing onto the face

necrotizing fasciitis

a flesh-eating bacterial syndrome; aggressive infiltration and destruction; causes tissue death; treatment includes debridement, IV antibiotic, and surgical

ophthalmia neonatorum

eye infections that can occur due to exposure to pathogens in the birth canal, but antibiotic creams are more now commonly used.

oral herpes

HSV-1; typically transmitted by direct oral contact between individuals

otitis externa

a condition that involves the inflammation of the ear canal; presents with ear pain, swelling, discharge, and hearing loss; acute or chronic; treatment includes debridement and topical drugs

papillomas

warts; are the expression of common skin infections by human papillomavirus (HPV) and are transmitted by direct contact; Vaccination is the treatment

papule

a small, raised and well-defined bump in the skin: can appear in a variety of shapes, colors, and sizes; a type of skin lesion

purulent

refers to the presence of pus, which is a thick, yellowish fluid that is typically a sign of infection

pustule

a small inflamed elevation of the skin that is filled with pus; a type of skin lesion

pyocyanin

a blue pigmentation resulting from a wound; a blue secondary metabolite; has the ability to oxidize and reduce other molecules, therefore kill microbes that compete against P. aeruginosa; very resistant; treatment includes polymixin b, gentamicin, and fluoroquinolones

pyoderma

skin infections that are purulent(has pus)

pyoverdin

are fluorescent siderophores produced by certain pseudomonads; are important virulence factors, and are required for pathogenesis in many biological models of infection; very resistant; treatment includes polymixin b, gentamicin, and fluoroquinolones

ringworm

In the group of “tineas”; also reffered to as tineas corporis; tineas on the body that often produce lesions that grow radially and heal towards the center, this causes the formation of a red ring

roseola

a mild viral infection usually caused by human herpesvirus-6 (HHV-6) and occasionally by HHV-7. It is spread via direct contact with the saliva or respiratory secretions of an infected individual, often through droplet aerosols. It is very common in children, with symptoms including a runny nose, a sore throat, and a cough, along with (or followed by) a high fever

sebaceous glands

small glands in the skin that produce and secrete sebum, an oily substance that helps lubricate and waterproof the skin and hair; they are most abundant on the face, scalp, and upper back; plays a crucial role in maintaining the health of the skin by moisturizing it and protecting it from drying out; excessive sebum production can lead to oily skin and contribute to conditions like acne

sebum

an oily substance produced by the sebaceous glands in the skin; helps to moisturize and protect the skin and hair

staphylolysins

are a group of enzymes produced by staphylococcus bacteria that can lyse or destroy red blood cells; a hemolysin; are considered virulence factors and play a role in the pathogenesis of staphylococcal infections

stratum corneum

the outermost layer of the epidermis, which is the outermost layer of the skin; composed of dead skin cells, acts as a protective barrier, preventing water loss and protecting the underlying layers of the skin from external factors

superficial mycoses

fungal infections that affect the outermost layer of the skin (epidermis), like skin, hair, and nails; caused by a variety of fungus such as dermatophytes, yeasts, and molds

suppurative

a term used to describe a disease or condition in which a purulent exudate (pus) is formed and discharged

sweat glands

small, tubular structures in the skin that produce sweat; found all over the body and play a crucial role in regulating body temperature

tinea corporis

ringworm

tinea cruris

jock itch

tinea pedis

athletes foot

tineas

a group of cutaneous mycoses that are caused by dermatophytes, fungal molds that require keratin, a protein found in skin, hair, and nails, for growth

ulcer/ulceration

a break in the skin or mucous membrane with loss of surface tissue, disintegration and necrosis of epithelial tissue, and often pus

vesicle

compartments formed by a lipid bilayer separating its contents from the cytoplasm or a fluid-based extracellular environment; a type of skin lesion

viral conjunctivitis

a highly contagious acute conjunctival infection usually caused by an adenovirus; characterized by irritation and watery discharge

wheal

a raised, itchy bump