B4-068 Pyogenic Model Flashcards
responsible for 80% of pus forming infections
S. aureus
mixture of living and dead neutrophils, bacteria, and cellular debris
pus
pus usually forms in an area of […] infection
persistent
circumscribed collection of pus associated with infection is called an
abscess
abscesses are relatively inaccessible to
2
antibiodies and antibiotics
need to be drained
TLR activates
macrophages
gram +
grapelike clusters
S. aureus
patient populations most likely to be colonized with S. aureus
3
- healthcare workers
- diabetics
- dialysis patients
S. aureus clings to nasal epithelial ligands via
2
clf-B
IsdA
main site of colonization with S aureus
anterior nares
tender pustule involving hair folllicle
folliculits
small abscess that exudes purulent material from a single opening
furuncle
aggregate of furuncles with several openings
carbuncle
unilateral warmth, erythema and tenderness of the joint
septic arthritis
high fever, peripheral emboli
endocarditis
risk factors for endocarditis
5
- prosthetic heart valves
- cardiac abnormalities
- IV drug use
- IV catheter
- bacteremia
can cause early infection in cystic fibrosis
S aureus
catheter associated infections are usually associated with
S. epidermidis
UTIs in sexually active young women are often due to
S. saprophyticus
the capsule of S. aureus helps to resist
phagocytosis
binds to the heavy chain of antibody, can inhibit opsonization
protein A
S. aureus
S. aureus can activate the classical complement pathway via
Protein A
binds fibrinogen and causes production of fibrin
coagulase
S. aureus
breaks down fibrin and blood clots
staphylokinase
S. aureus
- exotoxin
- causes leukocyte destruction and necrosis in skin and lungs
Panton-Valentin leukocidin (PVL)
S. aureus (less than 5% of strains)
- result in scalded skin syndrome
- fever, erythema, blisters
- positive Nikolsky’s sign
2
ETA, ETB
exfoliatin toxins
- localized scalded skin syndrome
- primarily in infants and young children
- culture positive
- highly communicable
- Nikosky’s negative
bullous impetigo
enterotoxins A-E and G-I are resposible for
food poisoning
bind to MHC class II and interact with beta chain causing non-specific activation
superantigens
enterotoxins A-E and G-I
often localized to the gut but can be fatal if systemic
enterotoxins
associated with stains that produce TSST-1
toxic shock syndrome
also enterotoxin B and C
fever
diffuse macular rash (sunburn)
hypotension
with systemic involvement
toxic shock syndrome
[…] patients are much more susceptible to serious infections with S aureus
neutropenic
produced by macrophages to recruit neutrophils
IL-8
IgG binds to antigens on S. aureus and attach to phagocyte via
FcyR
type II hypersensitivity
S. aureus activates what two complement pathways?
- classical -via antibody binding
- alternative via teichoic acid
C3b binds to bacteria and is broken down by Factor I into
iC3b
iC3b binds to CR3 and CR4 allowing for
phagocytosis
recognition of S. aureus by […] on macrophages and dendritic cells is the most important activator of the innate system
TLR2
women who experience TSS have lower antibodies against
TSST-1
possible vaccination development
most common cause of abscesses in humans
S. aureus
- gram positive
- high temperature tolerant
- haloduric
- beta hemolytic
- yellow color on mannitol salt
s. aureus
most usual source of staph enterotoxin food poisoning
food preparer has S. aureus on hands
- Gram positive
- catalase positive
- coagulase positive
- cocci
S. aureus
bacterial endocarditis in IV drug users is most commonly caused by
2
Staph or strep
Protein A binds to human IgG and activates
classical complement pathway
Protein A can bind to the […] chain of Ig
H
what makes protein A a super antigen?
- binds to H chain of Ig
- on B cells this causes a nonspecific activation of that B cell
activates plasminogen to form plasmin
staphylokinase
causes bullae, peeling and positive nikolsky sign
staphylococcal exfoliatin
which aspect of the immune system is most crucial for protection against S. aureus?
opsonization
plays little role in destroying gram positive organisms
MAC