Infectious Diseases

Question 1

What layers are different soft tissue infections associated with? Name 5

Answer 1

Folliculitis - hair follicle
Impetigo - stratum corneum
Ecthyma - epidermis
Erysipelas, Cellulitis - dermis and subQ fat
Necrotizing fasciitis - fascia, fat, muscle
Myositis - muscle layer

Question 2

What is the cause of skin erythema?

Answer 2

Immune related microvascular dilation

Question 3

What is Panton-Valentine leukocidin determinant (PVL)?

Answer 3

Virulence factor associated with staphylococcus isolates
Produces two proteins that are associated with destruction of human leukocytes and erythrocytes
associated with virulent strains that clinically produce furunculitis, cellulitis, abscesses

Question 4

List 6 DDx considerations in cellulitis

Answer 4

Foreign body response
Osteomyelitis
Septic arthritis
Envenomation
Fasciitis/myositis
Post surgical wound healing
Burns

Question 5

Which patients may require inpatient management of soft tissue infections?

Answer 5

Hemodynamic instability
Immunocompromised
Diabetic or significant medical comorbidities
Social - homeless, unable to follow up
Rapidly progressing
Suspect deeper infection (sepsis, bullae, crepitus)
Seeding of other sites (endocarditis, joints)

Question 6

What are the top 2 bugs implicated in soft tissue infections?
What is another pathogen to consider in the

Answer 6

Staph aureus/Strep pyogenes

Consider H. influenza (significant decrease since vaccinations)