Skin and Soft Tissue Infections

Skin

The body’s first line of defense against microbial infection

Epidermis

Outermost layer of skin

Dermis

2nd layer of skin. Contains sweat glands, hair follicles, and oil glands

Fascia

Thin bands of connective tissue that wraps around and supports various structures

Hyaluronic acid

Found in epidermis, dermis, and fascia, acting as lubricant

Sebum

Oils substance produced by sebaceous glands in skin

Perspiration

Watery substance produced by sweat glands that contains salt

What does the normal skin flora do?

• acts as competitive inhibitors of pathogenic organisms

• adapts to high salt, exposure to elements, and lack of nutrients

• adapts to the acidic pH of skin

What is the difference between transient colonizers and colonization that can infect with a break in the skin?

Transient colonizer- colonized body site and does not remain permanently

Colonization- long term and can become harmful

What are 2 gram positive cocci species that are normal skin biota?

Staph epidermidis and Streptococcus spp

What are 2 gram positive bacilli species that are normal skin biota?

Cutibacterium acnes and Corynebacterium spp

What is a known fungi spp of normal skin biota?

Candida

What is the MOST COMMON bacteria causing skin and soft tissue infections?

Staph aureus

Clenched Fist Injury

Eikenella corrodens

Strawberry Tongue

Scarlet fever: streptococcus pyogenes

Koplik’s Spots

Measles

German Measles

Rubella virus

Slapped Cheek

Fifth Disease: Parvovirus B19

Roseola Infantum

6th disease: Human Herpes Virus 6

Kaposi Sarcoma

Human Herpes Virus 8

Creeping eruption

Hookworms

Elephantiasis

Wuchereria bancrofti and Brugia malayi

Gliding motility

Capnocytophaga

Cat Scratch Fever

Bartonella henselae

Breadcrumb colonies

Nocardia

Dermatitis

Inflammation of the skin typically infecting the outer layers of skin

Dermatitis - Intertrigo

Noninfectious inflammatory cutaneous infection: body areas subjected to heat, moisture, and friction

Dermatitis - Thrush

Candidiasis involving the oral mucosa

Dermatitis - Erythrasma

Superficial, chronic skin infection in the keratinized layer of epidermis

Dermatitis - Dermatophytosis

Fungal infection that colonizes the keratinized surfaces of the skin

Pyoderma

Broad term for various skin infections that produce pus

Pyoderma - Impetigo

Erythematous lesion that may be bullous or non bullous

Erysipelas

superficial cellulitis that involves the epidermis, dermis, and lymphatic channels

Erysipeloid

Superficial soft tissue infection caused by Erysipelothrix rhusiopathiae

Anthrax

Skin lesions that can develop from papule to blister to eschar

Cellulitis

Diffuse spreading infection involving deep layers of the dermis, causing inflammation

What is the main causative agent of Cellulitis?

Staph aureus

Parnoychia

Infection of the cuticle surrounding the nail bed

Folliculitis

Inflammation or infection of hair follicles

Furuncles

An abscess that begins as red nodule, progressing to a painful, pus filled boil

Carbuncles

Furuncles coalesce and spread more deeply into the dermis and subcutaneous tissues

Hidradenitis Suppurativa

Recurrent infection of the apocrine sweat glands. Nodular swellings that drain and can cause scarring

Human Bites/Closed fist injuries

S. aureus, Strep spp, Eikenella corrodens

Animal bites most often from domesticated animals

Pasteurella multocida

Mycetoma

Chronic subcutaneous infection often infecting the feet

Chromomycosis

Chronic subcutaneous spreading mycosis - scaly lesions, usually on lower extremity

Phaeophyomycosis

Subcutaneous nodules with deeper involvement - usually caused by Dematiaceous fungi

Mucormycosis

a disease resulting rom members of the order Mucorales

Nodular Lymphangitis

Inflammatory nodules along lymphatic vessels - Sporotrichosis, Nocardia, Mycobacterium

Staphylococcal Scalded Skin Syndrome (SSSS)

Blistering skin condition primarily seen in children under 5 years - S. aureus

Nikolsky Sign in a clinical symptom of SSSS, what is it?

Seperation of the epidermal layer just from touch

Toxic Shock Syndrome

Caused by toxins from S. aureus stains that activate cytokines released from lymphocytes and macrophages

Scarlet fever

Caused by SPE-producing S. pyogenes. Conjunction with strep throat