Skin/Soft Tissue Infections Flashcards
Define cellulitis
Inflammation of the skin and subcutaneous tissue
What causes cellulitis?
Infection
Differentiate erysipelas from cellulitis
Erysipelas: upper dermis and superficial lymphatics
Cellulitis: deeper dermis and subcutaneous fat
List some predisposing factors for cellulitis
Break in skin barrier Edema/water retention Skin conditions Immunosuppression Co-morbidities Procedures other infections...
What are the most common bugs that cause cellulitis?
Strep and Staph
How do you get eikenella corrodens?
Human bite
How do you get pasteurella multocida?
Cat bites
How do you get capnocytophaga canimorsus?
Dog bites
Which pathogen is most associated with purulent cellulitis?
CA-MRSA
WHich species tend to cause non-purulent cellulitis?
MSSA Staph and Strep
What causes methicillin resistance in staph?
presence of the MecA gene
Name two predisposing factors to diabetic foot ulcers
Neuropathy
Peripheral vascular disease- (slow healing)
How do you treat infected diabetic foot ulcers?
Treat polymicrobial - usually they have been around for a long time and have been seeded with many different strains of bacterial
Name 3 potentially fatal complications of cellulitis
Necrotizing fasciitis
Sepsis
Toxic Shock Syndrome (2% fatal)
Describe the blood cultures of someone with staph toxic shock
Classically they are negative
What is the clinical pictures of someone with toxic shock
Fever, hypotension
Macular erythematous rash
Multi-organ involvement
Later- desquamation of palms/soles
Describe the pathogenesis of staph txx
TSS toxin -1 release –> massive cytokine production
Differentiate the rash see in staph toxic shock vs strep toxic shock
Staph: diffuse rash
Strep: diffuse rash only seen in 10% of cases - more commonly positive cultures
What is the clinical presentation of necrotizing fasciitis?
Pain out of proportion to exam
Rapidly evolving
Fever, hypotension
Skin: initially minimal changes –> dark/necrotic/gangrene
What is unique about the pathogenesis of pseudomonas cellulitis/nodules?
Rather than coming from outside –> in, bacteremia with pseudomonas can cause septic emboli to the skin and cause necrotic nodules on the skin (inside out)
