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Flashcards in SSTI's Deck (18):
1

What layer(s) of skin do the following diseases effect?
Impetigo
Erysipelas
Cellulitis
Necrotizing fasciitis

Impetigo - epidermis
Erysipelas - dermis
Cellulitis - dermis and subQ
Necrotizing fasciitis - subQ and fascia

2

Erysipelas
Characteristics
Cause
Tx

Bright red w/ sharp borders, typically affecting face. Raised, indurated, and painful.
Caused by GAS.
Tx w/ penicillin.

3

Cellulitis
Characteristics
Cause of purulent
Cause of nonpurulent

No sharp borders. Deeper. Red, hot, swollen.
Purulent caused by S aureus (>50% MRSA)
Nonpurulent caused by beta-hemolytic strep, especially GAS. More common.

4

What is most important and overlooked aspect of cellulitis?
What is tx?
What increases risk?

Lymphadenopathy / lymphedema
Tx w/ support stockings or ACE wraps (not diuretics)
Prior cellulitis increases risk of lymphedema.

5

Portals of entry for cellulitis (5 things)

Tinea pedis (most common), ulcer (diabetics), trauma, eczema, psoriasis

6

Diagnosing cellulitis (4 things)

•Blood cultures if hospitalized (low yield)
•Needle aspiration – good for fluctuant (fluid-filled) areas such as bullae, and immunocompromised pxs
•ASO (antistreptolysin O) titer good for GAS
•MRSA swabs in nose, groin, and axilla

7

When is AB prophylaxis used?
Which AB's?

AB prophylaxis may be used for recurrent cellulitis (2+ episodes / year) or in pxs where lymphedema is difficult to tx (post-mastectomy). Daily low dose of penicillin, dicloxacillin, clindamycin, or erythromycin for 1 year or longer.

8

Causes of cellulitis in the following settings:
Fresh water trauma
Salt water trauma
Butcher
Periorbital
Inmates / MSM / Athletes / Children
Fish tank
Dog / cat bite

Fresh water trauma - Aeromonas hydrophila
Salt water trauma - Vibrio species
Butcher - Erysipelothrix
Periorbital - S aureus or GAS > 5 y/o
Inmates / MSM / Athletes / Children - CA-MRSA
Fish tank - Mycobacterium marinum
Dog / cat bite - Pasteurella multocida

9

Risk factors for necrotizing SSTI's (7 things)

Trauma, surgery, peripheral vascular disease, diabetes, obesity, alcohol / IV drug abuse, immunocompromised.

10

Clues to suggest severe SSTI's (5 things)

•Pain out of proportion to visible presentation
•Systemic toxicity – anion gap, creatinine, CK, shock, organ failure
•Rapid progression
•Necrosis, gangrene, bullae, cutaneous hemorrhage, crepitus (gas-forming)
•Anesthesia – due to nerve destruction

11

GAS Necrotizing Fasciitis
Characteristics
Affected sites (5 places)
Tx

Often background of skin lesion such as boil, abrasion, injection site, insect bite, or minor trauma.
SEVERE pain.
Swelling → bullae (clear → red/purple) → gangrene.
Systemic toxicity may cause shock and organ failure.
•Most commonly found in extremities, anterior abdominal wall, perineum, perianal area, and surgery sites.
•Tx w/ penicillin + clindamycin

12

Polymicrobial Necrotizing Fasciitis
Characteristic
Example of disease w/ characteristics, population, and organism.

Synergistic infection w/ aerobic and anaerobic bacteria.
Fornier's Gangrene - polymicrobial infection of perineum / scrotum. Most common in diabetics. Often involves Pseudomonas.

13

What type of necrotizing fasciitis is caused by salt water, shellfish, or plankton?
Sxs
Population

Vibrio vulnificus necrotizing fasciitis.
Causes large blisters / ulcers
Pxs: cirrhosis and CMI impairment

14

Gas gangrene
Caused by?
Mediated by?
Sxs
Tx

Clostridium perfringes
Toxin-mediated
Sxs - severe pain, edema, bullae, purple hue, "dirty dishwater" drainage, gas, and systemic toxicity.
Tx w/ debridement, penicillin, and clindamycin.

15

Diabetic foot infection
Acute caused by?
Chronic caused by?
Tx

Acute due to S aureus or Strep
Chronic ulcers often polymicrobial.
Tx w/ debridement, abscess drainage, amputation (if needed), and broad spectrum AB's.

16

Neutropenia
Common infectious organisms
Specific disease, organism, sxs, location
Tx

•Aerobic GNR (Pseudomonas, E coli), Staph, Strep
•Ecthyma gangrenosum – cutaneous vasculitis caused by Pseudomonas. Starts as painless red macule, which may progress to painful necrotic lesion. Often found in groin.
•Tx w/ broad spectrum AB including those against pseudomonas and MRSA

17

Human bites
Oral bacteria
Risk of diseases
Tx

•Oral bacteria: Strep, Staph, Hemophilus, Eikenella corrodens
•Risk of Hep B / C, syphilis, herpes, and HIV
•Tx w/ wound irrigation / cleansing, tetanus toxoid, AB’s (amox-clav, or fluroquinolones + clindamycin)

18

Dog / Cat bites
Organisms
Tx

•Pasteurella multocida and Capnocytophaga canimorsus
•Tx w/ wound irrigation / cleansing, AB’s (amox-clav, fluoroquinolones, or cefuroxime + clindamycin