Infections of Skin and Soft Tissues - Clinical Flashcards
What are the three classifications of S & ST infections?
Exogenous - new infections, from outside
Endogenous - from previous present organism
Toxin-mediated - (i.e. S. aureus exfoliative toxin / TSST)
What layer does impetigo infect and what are the causative organisms?
Epidermis
S. aureus and S. pyogenes
What layer(s) does erysipelas infect and what are the causative organisms?
Dermis
S. pyogenes
What layer(s) does cellulitis infect and what are the causative organisms?
Epidermis, dermis, subcutaneous
S. aureus and S. pyogenes
What layer(s) does folliculitis infect and what are the causative organisms?
Outer hair follicle
S. aureus
What layer(s) does furuncle infect and what are the causative organisms?
Deep in hair follicle
S. aureus
What layer(s) does carbuncle infect and what are the causative organisms?
Multiple deep hair follicles in combined area
S. aureus
What layer(s) does fasciiitis infect and what are the causative organisms?
Fascia
S. pyogenes, others
What layer(s) does gas gangrene infect and what are the causative organisms?
Skeletal muscle
Clostrium perfringens and others
What causes hot tub folliculitis?
Pseudomonas spp.
What causes lymphatic obstruction?
Streptococcus species
What bacteria enters in aquarium exposure?
Mycobacterium marinum
What bacteria enters in fresh water?
Aeromonas species
What bacteria enters in salt water?
Vibrio species (i.e. cholerae)
What bacteria comes from animal bites? What skin symptoms can it cause?
Pasteurella
Can cause cellulitis progressing to gangrene / necrotizing fasciitis
What disease is commonly spread via the fingers of HCW?
Herpes simplex
What is the causative agent of ecthyma gangrenosum?
P. aeruginosa, in neutropenic patients
How does impetigo differ between Staph and Strept?
Staph - boil / localized
Strept = honey-crust
What patient population is cellulitis particularly common in?
Diabetics - due to anaerobes fermenting their sugar (especially during neuropathy)
What population of patients is susceptible to cutaneous candidiasis and where does it occur?
Diabetics, occurs in sweaty / moist areas (skin folds)
Where does tinea versicolor occur?
Trunk or extremities
Where is tinea cruris?
The groin
What are the three fungal genera causing tinea infections?
Trichophyton
Epidermophyton
Microsporum
What is an endogenous infection?
An infection caused by an infectious agent that is already present in the body, but has previously been inapparent or dormant
What are two routes of endogenous skin and soft tissue infection?
- Direct extension - i.e. Herpes simplex activates to skin from the nerve, or draining nasal sinus seeds pathogen to bone
- Hematogenous - IV line displaces pathogens throughout bloodstream, allowing spread to soft tissues (i.e. endocarditis)
What is secondary syphilis?
The second stage of syphilis, with lesions around the body, especially palms and soles
Define exanthem. What diseases is this common in?
A widespread rash, common in measles and german measles, as well as chicken pox
What type of skin finding do herpes infections have?
Vesicles
Labialis: lips
Genitalis: ulcers
Zoster: Dermatomal
What type of skin lesions are present with hand, foot, and mouth disease?
Vesicles (blisters)
*Cocksackie virus
What causes scarlet fever?
erythogenic toxin of S. pyogenes, causing spotted lesions around body
What is used to treat a CA-MRSA infectino causing a boil?
Always drain / lance boils
Give oral TMP/SMX, clindamycin (good for staph, strept, and anaerobes), doxycycline (good for CA-MRSA)
