Bacterial Skin Infections Flashcards Preview

D&T 1: Exam 2 > Bacterial Skin Infections > Flashcards

Flashcards in Bacterial Skin Infections Deck (12)
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1
Q

M-protein

A

Important potential virulence factor of S. pyogenes; causes AGN

*can also be DNAse (+), hyaluronidase (+), or have Streptolysin O or S

2
Q

Impetigo

A

Contagious superficial infection seen in children; purulent w/ crusting

  • Can also be bullous or pustular w/ crusted lesions; presents in warm, humid times
  • Caused by S. aureus or S. pyogenes
3
Q

Bullous impetigo

A

Assoc. w/ Scalded Skin Syndrome; caused by exfoliative toxin A from S. aureus

  • Destruction of intracellular connections in the epidermis
  • Highly contagious
4
Q

Erysipelas

A

A sharply demarcated, salmon red lesion that is a superficial erythematous lesion (does not go to dermis)

-Presents in the face or leg

**ALWAYS CAUSED BY S. PYOGENES

5
Q

Cellulitis

A

Elevated and inflamed lesion accompanied by lymphadenitis of the draining node

  • MOST COMMON CAUSE IS S. AUREUS
  • Also caused by S. pyogenes, H. influenzae (unvaccinated), and P. multocida (after dog/cat bite)
6
Q

Necrotizing Fasciitis

A

Type I: Occurs after surgery and in pts. w/ diabetes; mixed Gram pos and neg infxn

Type II: Caused specifically by S. pyogenes

  • C. perfringens can cause myonecrosis and produce gas in the skin
  • Extensive tissue destruction, thrombosis, destruction of fascia and fat (subcutaneous layer)
7
Q

V. vulnificus

A

Causes severe necrotizing fasciitis characterized by initial swelling, erythema, and eventual necrosis

  • Occurs after exposure to contaminated sea water
  • Very fatal (~50%)
8
Q

Ecthyma gangrenosum

A

Causes tissue necrosis in neutropenic pts. w/ P. aeuruginosa bactermia

-Can also cause “bath tub folliculitis” or infect burn pts.

9
Q

Leprosy

A

Tuberculoid: Red-blotchy lesions that are non-infective
=»Treat w/ rifampin, dapsone

Lepromatous: Diffuse lesions that are highly infective
=»Treat w/ rifampin, dapson, and clofazimine (possibly for life)

10
Q

Bacillus anthracis characteristics

“King Anthra’s Axe”

A

Spore-forming GPR; encapsulated w/ D-glutamic acid

Contains exotoxin w/ 3 parts:

Edema factor (cya)- AC that increases intracellular cAMP inhibiting the flow of ions and water

Lethal factor (Lef)- protease that induces macrophages to release cytokines and initiate shock

Protective antigen (Pag)- promotes the entry into phagocytic cells only

Diagnosis: Examination of material from lesions; grows non-hemolytic, sticky colonies on culture

Treatment: Penicillin, Cipro, and Doxy for 60 days
-Short-term vaccine also available

11
Q

Inhalation anthrax

A

Inhalation of aerosolized spores =» fever, SOB, malaise, chest/abdominal pain
-Death 3 days later

-Will also see mediastinal widening on x-ray

12
Q

Cutaneous anthrax

A

Painless papule forms at site of inoculation that =» necrotic, black eschar

-Localized tissue necrosis caused by toxin release