Unit 14. Infectious Diseases Affecting the Skin and Eyes

Anatomy of the skin image

-Stratum Corneum consists of keratinized cells and is constantly shedding to get rid of fungi

Defenses of the skin 

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Defenses of the Normal Biota of the skin

Bacteria such as: Staphylococcus, epidermis, propionibacterium, corynebacterium, lactobacillus, bacteroides, prevotella, haemophilus: yeasts like Malassezia, Candida

Types of skin lesions: Macule

flat demarcated lesion determined by color change, ex: freckle, tinea versicolor

Types of skin lesions: Papule

small elevated solid bump, ex: warts, cutaneous leishmaniasis

Types of skin lesions: Maculopapular rash

flat-slightly raised colored bump, ex: measels, rubella, fifth disease, roseola

Types of skin lesions: Plaque

elevated flat topped lesion, >1cm, ex: psoriasis

Types of skin lesions: vesicle

Elevated lesion with clear fluid, ex: chickenpox

Types of skin lesions:Bulla

Large (wide) vesicle, ex: blister, gas blister in gengrene

Types of skin lesions: Pustule

Small, elevated lesion filled with purulent fluid (pus), ex: Acne, smallpox, mucocutaneous leishmaniasis, cutaneous anthrax

cyst

raised encapsulated lesion, usually solid or semisolid when palpated (severe acne)

Purpura

reddish purple discoloration due to blood in small areas of tissue, does not blanch when pressed (meningococcal bloodstream infection)

petechiae

small purpura (meningococcal bloodstream infection)

scale

flaky portions of skin separated from deeper portions (ringworm, athlete's foot)

MRSA skin and soft tissue infections chart, treatment & causative organisms

MRSA Skin & soft tissue infections: what is it

-Raised, red, tender, localized lesions, often featuring pus and feeling hot to the touch

what is Impetigo & what causes it

• Superficial bacterial infection that causes the skin to flake or peel off, Superficial, itchy lesions

• Caused by Staphylococcus aureus, Streptococcus pyogenes, or both

Impetigo chart treatment

Cellulitis identification & causation

• Fast spreading infection in the dermis and subcutaneous tissues, red lesions, often surrounded by red lines, signs of inflammation

• Caused by bacteria or fungi. Most common, S.aureus or S. pyogenes/other fungi

cellulitis treatment

Scalded skin syndrome identification & causation

• Dermolytic condition, affecting mostly newborns/babies

• Bullous lesions, forming large blisters that evolve to widespread desquamation

-Caused by toxigenic S. aureus bearing a lysogenic phage.

scalded skin treatment

Gas gangrene image

gas gangrene identification & causation

• Clostridial myonecrosis, an aggresive infection of muscles

• Local necrosis of muscles and nearby tissues with gas bubbles.

• Caused by Clostridium perfringens, a spore-forming, toxigenic, strictly anaerobic Gram-positive bacterium

gas gangrene treatment

Vesicular/pustular rash diseases

chickenpox, smallpox, HFMD, monkeypox

Chickenpox identification & causation, & treatment

-Maculopapular lesions evolving to fluid-filled vesicles. Centripetal distribution.

-caused by Herpesvirus 3 (varicella),

-no treatment in uncomplicated cases,acyclovir for high risk

Smallpox identification, causation, & treatment

-Fever and malaise followed by rash spreading from the pharynx. Maculopapular lesions evolving to vesicles and pustules

-caused by Variola virus.

-Treatment: cidofovir vaccine

Hand, foot, & mouth disease (HFMD)

-caused by Enteroviruses (Coxsakie) on Babies and children. Fever, sore throat, and malaise. First lesions in mouth,

-no known treatment

which of these is caused by herpes virus

Roseola

Rubella 

-Caused by Rubella virus/rubivirus

-mild red rash, last roughly 3 days

-no treatment

Measels(Rubeola)

-rash that starts on head & spreads over whole body, last over a week, sore throat/dry cough, headache

-caused by measels virus/morbillivirus

-treatment: vitamin A &  antibiotics for secondary bacterial infections

Fifth disease(Erythema infectiosum)

-”slapped face” rash, sreads to limbs & trunk, confluent rather than bumps

-caused by Parvovirus B19

-no treatment

Roseola

-High fever which preceded rash stage, rash not always present

-caused by human herpesvirus 6

-no treatment

Molluscum contagiosum

•wartlike eruption

-Smooth, waxy nodules on the face, trunk, and limbs

•Caused by molluscum contagiosum viruses

-no treatment, can be removed at home

Warts (papillomas)

•wartlike eruption

-Benign, squamous epithelial growths, Painless, elevated, rough lesions

•Caused by human papillomaviruses

-treatment:home treatments & cryosurgery

Leishmaniasis

•Large pustular skin lesions,Zoonosis transmitted by bytes of sand flies

•Caused by Leishmania spp.

-treatment: sodium stibogluconate

Cutaneous anthrax

•Large pustular skin lesions, Papular lesions that become necrotic and rupture to form a painless, black eschar

•Caused Bacillus anthracis, a spore- forming Gram-positive bacterium

•Treatment: ciprofloxacin, doxcycline, levofloxacin

Cutaneous mycoses

-fungal infections affecting only the stratum corneum

-caused by trichophyton, microsporum, epidermophyton.

-treatment: topical tolnaftate, itraconazole, terbinafine, miconazole, thiabendazole, oral terbinafine

Superficial mycoses

-benign infections that do not cause inflammation

-caused by Malassezia species

- treatment: topical antifungus

defenses of the eye chart

Normal Biota of the eye

corynebacterium, staphylococcus epidermis, micrococcus, & streptococcus species

Conjunctivitis

• Infection of the conjunctiva, inflammation, discharge, pain, redness, photophobia

neonatal conjunctivitis

-caused by chlamydia trachomatis or neisseria gonorrhoeae

-babies <28 days old

-treatment: oral antibiotics

Bacterial conjuntivitis

-caused by streptococcus pneumoniae, staphylococcus aureus, haemophilus influenzae

-mucopurulent discharge

-treatment: gatifloxacin or levofloxacin ophthalmic solution

viral conjunctivitis

-caused by adenoviruses & others

-serous/clear discharge

-treatment: none

Trachoma

-caused by Chlamydia trachomatis

-infection of the eye's epithelium, inflammation & discharge in conjunctiva, followed by infiltration of WBCs.may lead to impaired vision

-treatment: Azithromycin or topical erythromycin

Keratitis

•caused by reactivated herpes simplex virus

-Infection of deep eye tissues that may lead to corneal destruction

-treatment: topical trifluridine and or oral acyclovir

Trachoma and Keratitis chart

River blindness

• Caused by the worm Onchocerca volvulus, infected with Wolbachia

• Helminth(worm) infection transmitted by bytes of black flies, worm can often be seen in eye

-treatment: ivermectin