Toxic Shock and Meningo Flashcards
How do superantigens activate the immune system?
Super antigens produced (by S. aureus or S. pyogenes) directly bind to the MHC II molecule AND the Vß subunit of the CD4+ T Cell Receptor.
They don’t activate traditionally, they bind to the SIDES of the receptors (outside MHC peptide groove).
What’s the difference between traditional CD4+ activation and superantigen activation?
Traditional activation by some foreign peptide will only activate 1/100,000 CD4+ cells on a good day.
Superantigen activation will activate 20% OF ALL YOUR CD4+ CELLS. Hence the big reaction.
What’s the pathophysiology of a superantigen mediated toxic shock syndrome?
The superantigens made link up with a CD4+ cell and antigen presenting cell, binding to the MHC II complex and TCR. This turbo charges the CD4+ cell.
Macrophages make IL-1, IL-6, and TNF, which sounds the alarm. IL-8 is made to recruit other WBCs.
The liver starts making acute phase reaction proteins to protect the body, the blood vessel’s endothelium gets really permeable, allowing WBCs to get into tissue.
The endothelial cells make IL-8 as well, which tells WBCs to get into tissue and phagocytose.
Temperature is increased to stop any would-be invaders from growing well (like turning up the AC to get in-laws out of your house), PMNs are activated, recruited, and start carpet bombing, damaging tissue along with anything foreign (not how you would get in-laws out of your house).
The response is excessive, leading to a cytokine storm, causing capillary leak, tissue damage, multi organ failure and death.
How does one diagnose Staphylococcal Toxic Shock Syndrome?
Fever > 102°F
Hypotension (systolic BP < 90 mmHg)
Diffuse macular erythroderma (rash)
Desquamation at 1-2 weeks
3 or more organ systems involved (GI, renal, liver, muscular, CNS, mucus membranes and/or thrombocytopenia)
What must be ruled in/out for diagnosis of Staph TSS?
Rule out:
measles, leptospirosis, rocky mountain spotted fever (serology)
other organisms (negative blood cultures)
Rule in:
S. aureus by isolation – NOT REQUIRED
Risk factors for Staph TSS?
THE CRIMSON TIDE:
tampon in for greater than 8 hours (the hunt for red october)
packing your nose to stop bleeding (shouldn’t have let them punch you in the nose in the first place…)
recent surgery
wound
post partum
Signs and symptoms of Staph TSS?
That headache, confusion, sunburn like rash (hands, feet especially), photophobia, myalgias, pelvic pain, sore throat, hypotension, fever, vomiting, diarrhea so you can rest medicine.
Actually, considering the symptoms, it sounds more like a mix between a bad date and and alien abduction…
How does one diagnose Streptococcal Toxic Shock Syndrome?
Isolation of Streptococcus pyogenes from a normally sterile site (tissue biopsy, surgical wound, CSF, pleura, peritoneal fluid, blood)
Hypotension (systolic BP < 90 mmHg)
AND
2 or more of the following:
renal insufficiency, coagulopathy, increased liver enzymes, adult respiratory distress syndrome, soft tissue necrosis, and/or erythematous macular rash (may desquamate). It’s beginning to look a lot like Christmaaaaaas…
Risk factors for Strep TSS?
any disease compromising skin or mucosal surfaces
wounds
chickenpox
use of NSAIDS
pregnancy
underlying comorbidities
(sounds like a step-by-step list for 19th century family making)
Strep TSS associated with?
MO: invasive, skin/soft tissue infections (necrotizing fasciitis, myositis)
patients will frequently have pain at the site of the skin infection.
Types of Staph TSS?
Menstrual (super absorbant tampons become a FOB for S. aureus as it produces TSST-1)
Nonmenstrual:
post surgery, skin infections, abscess, wounds (usually burn victims), post influenza staph pneumonia
A superabsorbant tampon??? Why???
Unclear!
Their theory: increased intravaginal O2 from tampons, high protein, neutral pH
My theory: don’t we culture Staph on blood agar plates?…
In Staph TSS, is there usually pain at the site of infection?
NO
Staph vs Strep TSS
Skin/soft tissue infection
Staph: UNCOMMON
Strep: COMMON
Severe pain at skin
Staph: RARE
Strep: COMMON
Diffuse rash
Staph: VERY COMMON
Strep: UNCOMMON
Bacteremia
Staph: RARE
Strep: COMMON
Mortality
Staph: 3-5%
Strep: 5-10%
Treatment of Toxic Shock Syndrome?
IV Fluids
Thorough search for site of infection (tampon? foreign bodies? abscess drainage, wound debridement)
Antibiotics (MSSA-nafcillin, MRSA-vancomycin, GAS-penicillin G)
Clindamycin to block toxin production
Maybe IVIG therapy