Flashcards in 8 Staphylococcus Pathogenesis Deck (36):
What are key symptoms of Schlievert's story of Infectious Endocarditis?? (4)
-Severe night sweats
-Weight loss 30 lbs
What are key signs of Schlievert's story of Infectious Endocarditis? (4)
-Abnormal heart sounds
-Cultures show catalase-positive, coagulase-positive gram-positive cocci (S. Aureus)
-Not in story but often: metastatic abscesses
What happens to the physician after hospitalization in Schlievert's story? (4)
-stroke left side, takes 2 yrs to recover movement and 1 yr to recover speech
-Hospitalized 6 weeks w/ "suportive care"
-Lost 60 lbs
-Practices medicine today.
What are the common causes of infectious endocarditis? (3)
-Staph aureus [45%] highly valve-destructive
-Viridans streptococci [35%]
-Enterococcus faecalis & faecium [15%]
What makes enterococcus faecalis & faecium so bad?
-highly antibiotic resistant, including to vancomycin. Can transfer this resistance to other gram-positives.
How do we treat infectious endocarditis? (4)
-manage complications (stroke)
What does staph aureus do to skin? (7) Important!!
Primary inflammation: boils (furuncles), carbuncles (multiple boils), pimples (folliculitis), paronychia (nail beds), impetigo, soft tissue abscesses, atopic dermatitis
What is staph aureus's virulence key is skin?
walling off organism by cell surface virulence factors, then spreading by secreted virulence factors
What does staph aureus do to mucous membranes thru inflammation? (6)
Primary inflammation (less inflammation than skin due to less alpha-toxin made by these strains):
sinusitis, chronic otitis media, bronchial pneumonia, urinary tract infection vaginal infection, enterocolitis
What does staph aureus do to mucous membranes when non-inflammatory? (3)
-Scalded Skin syndrome
-Toxic shock syndrome (TSS)!! (including menstrual)
-Staphylococcal food poisoning (pre-formed toxins)
What is scalded skin syndrome?
-1-2 day old infant skin peeling due to exfoliative toxins (becomes very susceptible to secondary serious infections
What are symptoms of staph food poisoning?
vomiting, diarrhea 2-8 hrs after eating, lasts up to 48 hrs
What systemic infections does staph aureus cause? (5)
What is septicemia?
high fever, hypotension, DIC & metastatic abscesses
[sound familiar from earlier lecture]
What are necrotizing fasciitis/myositis symptoms?
fever, necrotizing tissue damage often with TSS
[sound familiar from earlier lecture]
T/F S. aureus usually remains localized?
T/F S. aureus all give rise to systemic superantigens, and if so then which?
T, TSST-1, SEB, SEC
TSS: What cytokines?
IL1-B (fever), TNF-alpha & beta (hypotension), IFN-gamma, IL-2 (rash 7 other symptoms)
Menstrual TSS is most common in which type of tampon?
What is TSS often a complication of?
How is TSS defined? (6)
-Fever over 102 degrees
-hypotension systolic under 90
-rash (macular erythroderma)
-peeling of skin if survive
-3 mulit-organ changes
-Must rule out other causes
What if some criteria for TSS are missing?
-1 missing: "Probable TSS"
-More missing: "Toxin-mediated disease"
Name "other" systemic signs of staph infection (see photos) (3)
-gangrene (lack of perfusion from hypotension)
How do we treat staph aureus skin or mucous membrane infections?
antibiotics, surgery to drain abscess/furuncle, remove infected hair/nails
How do we treat more serious ones? (recall infectious carditis treatment earlier card)
-Debridement in necrotizing illness
-Activated protein C (drotrecogin-alpha if needed)
-Remove affected object (tampon etc)
-Influenze vaccine to prevent future post-influenze TSS
how to do prevention in hospitals? (don't memorize)
hand-wash, antibiotic sensitivity monitoring, dust low, monitor infected patients, monitor visitors
Coagulase-negative staph group includes what 3 pathogens?
staph epidermidis causes what 2 problems?
-Septicemia (number 1 cause) & endocarditis associated w/ catheterization biofilms. [due to PIA & cytolysins, rarely superantigen]
-UTI (urinary tract infection) associated w/ catheterization
Staph saprophyticus causes what problem?
Staph lugdenensis causes what problem?
How are the 3 coagulase-negative infections treated?
Same as S. aureus, except must decide if the primary infection is staph or if it only came from catheterization thru the skin
Do more inflammatory strains of staph live on skin or mucous membranes?
How does a fununcle (boil) form? (3 basic steps)
-staph inside skin.
-Fc of Ab's are binding to staph, but the cell surface virulence factors are secreted & clotting cascade walls it off in a furuncle.
-Once high density of bacteria inside, cell surface virulence factors turn off. Secreted virulence factors turn on & now it spreads to other areas of skin.
What is are the key differences in the way staph behaves when on mucosal surfaces? (2)
-Not walling itself off w/ coagulase
-Doesn't make much alpha toxin
Clotting in nailbeds is a strong sign of? (2)
-Endocarditis (staph or strep)