Necrotising Faciitis

Question 1

2 bacterial causes of toxic shock syndrome

Answer 1

Staph aureus

Strep pyogenes

Question 2

Toxic shock definition

Answer 2

Acute toxin-mediated illness resulting in shock and multi-organ failure
Usually from S aureus or S pyogenes
Shock is persisting hypotension despite adequate volume resuscitation requiring vasopressor support

Question 3

Toxins involved in toxic shock

1. 2 from S aureus
2. 1 from Strep

Answer 3

1. Toxic shock syndrome toxin-1 (TSST-1), Staphylococcal enterotoxins (SEB and SEC)
2. Streptococcal pyrogenic exotoxin A

Question 4

Super antigens

Answer 4

The toxins implicated in TSS
Binds as unprocessed proteins to both MHC II and to the TCR
Leads to non specific activation of T cells

Question 5

Staphylococcal Toxic Shock

Answer 5

Seen in association with highly absorbent tampons
Initial sx: fever, myalgias, GI upset
Can develop macular rash
Progressive hypotension/organ dysfunction
Skin desquamation occurs late
Rarely associated with bacteremia
Tx with source control and supportive care for hypotension

Question 6

Antibiotic management for staphylococcal toxic shock

Answer 6

Broad coverage: Vancomycin
Can step down to cloxacillin if MSSA identified
Consider adding clindamycin

Question 7

Streptococcal toxic shock

Answer 7

Invasive disease (bacteria isolated from a normally sterile site) associated with:
pre existing skin lesions, varicella infection in children, DM, injection drug use, post-partum setting
Higher rate of bacteremia in 60% of cases

Question 8

M protein

Answer 8

Group A strep
Critical virulence protein
Helps with adherence to epithelium
Assists in evading phagocytosis/antibody binding
May contribute to additional cytokine release

Question 9

Necrotizing Fasciitis

Answer 9

Severe and rapidly progressive infection of the muscle fascia and subcutaneous fat
Can involve the epidermis
Can involve adjacent muscle
Classically in the limbs (lower > upper)

Question 10

Type 1 vs 2 of necrotizing faciitis

Answer 10

Type 1: polymicrobial, including gram - and anaerobic organisms
Type 2: group A strep (mono microbial)

Question 11

Potential initial clues to necrotizing fasciitis

Answer 11

Severe pain out of keeping with clinical findings

Progressive edema beyond area of erythema

Question 12

Late clinical signs of nec fascitiis

Answer 12

Development of bullae
Evidence of gas in the soft tissues (crepitus)
Cutaneous anesthesia

Question 13

How is diagnosis of nec fas made?

Answer 13

Surgically

Biopsy for an urgent gram stain

Question 14

Antibiotic management for

1. Suspected necrotizing fasciitis
2. Proven GrpA strep

Answer 14

1. Vanco PLUS pip-tazo, +/- clindamycin
2. Penicillin PLUS clindamycin
   Minimum 14d if bacteremic - maybe more

Question 15

Rationale for using clindamycin in nec fasc

Answer 15

Penicillin is less effective once bacteria are in the steady state, but clindamycin remains active
Potential benefits of decreasing protein production (like M protein toxin)

Question 16

Rationale for using IVIG

Answer 16

Neutralization of the superantigens
Downregulation of chemokine receptors
Decrease in production of inflammatory cytokines
3 days of IVIG is helpful!