Necrotizing Soft Tissue Infections Flashcards
What tissue structures are involved in necrotizin soft tissue infections?
- skin
- subcutaneous tissue
- muscle
- fascia
What are the most common microbials to cause Toxic shock syndrome?
Staph and Strep spp.
What is the mortality rate of necrotizing soft tissue infections in dogs?
53%
What are the 4 types of necrotizing soft tissue infections?
Type I Polymicrobial
* mixed microbials
* anaerobes and aorobes
Type II Monomicrobial
* typically beta-hemolytic Streptococcus
Type III anaerobe monomicrobials
* often clostridial
* marine organisms
Type IV Fungal
List viurlent factors of streptococci
- exotoxin superangitens
- cell envelope proteinases
- hyaluronidase
- complement inhibitor
- M-protein
- protein F
- steptolysins
What radiographic finding is indicative of necrotizing soft tissue infections?
subcutaneous air –> indicates gas-producing organism
What are the histopath findigns of necrotizing soft tissue infections
fascial necrosis
myonecrosis
angiothrombotic microbial invasion
liquefactive necrosis
Why are penicillins often not effective against necrotizing soft tissue infections?
Streptococcus Group A can go into a stationary phase at high tissue concentrations - makes penicillins ineffective
Clindamycin is effective against the stationary phase
Why are fluoroquinolones contraindicated in necrotizing soft tissue infections
can cause bacteriophage-induced lysis of S. canis»_space;enhances pathogenicity
What causes TEN?
Toxic epidermal necrolysis
lymphocyte mediate cyotoxicity –> T lymphocytes release granulysin and natural killer cells are activated –> keratinocyte apoptosis
What is the mainstay treatment for TEN?
steroids
What are the most common streptococci to cause NSTIs in small animals?
beta-hemolytic streptococci of Lancefield group G (e.g., streptococcus canis)
other more common ones in dogs: staph and E.coli
What is Fournier’s gangrene?
variant of NF involving perianal area
What are conditions shown to potentially predispose to NSTI?
- immunomodulating conditions 19% (e.g., cushings, hytpothyroidism, IMHA, etc.)
- steroids administrared 13%
- NSAIDs administered 17%
- prior skin barrier compromise 17%
What is vimentin?
intermediate muscular filament - upregulated in injured skeletal muscle and can act as a tether for streptococci
