EX2 Staphylococcus - Daniels Flashcards
Are staph gram + or -
gram +
Is staph motile
no; non mitile
Does staph form spores
no; non-spore forming
What level of oxygen does staph prefer
facultative anaerobes
Are staph catalae negative or positive
positive
This species staph is coagulase positive
S. aureus
This causes the highest burden of disease in people
S. aureus
S. aureus is the most common causative agent of what diseases
integumentary and wounds bacteremia aspiration pneumonia UTI toxic shock syndrome scalded skin syndrome food poisoning
Where does S. aureus live and where is it most likely to be encountered
lives on and around people; 30-40% prevalence in nasal carriage
muco-cutaneous junctions
hearty environmental survival (clothes, surfaces)
commensal
What surfaces does S. aureus enter through
skin/follicles (wounds/ burns/bite marks)
mucosal surfaces
What can vary the spread of S. aureus
bacterial inoculum
host immunocompetence
location of infection
bacteremia + immune compromise = trouble
What type of population is at risk for severe S. aureus infections
young children/elderly diabetics immunosuppressive HIV dialysis IV drug users
MSCRAMMs are what
microbial surface components recognizing adhesive matrix molecules
enhance the ability to colonize and invade
What is an example of a MSCRAMM and what is so important about it
fibronectin
key player in the ECM function of adhesion
True or False
Collagen is a MSCRAMM
True
What assists fibronectin in binding
clumping factors; clot formation
What is pus
acute suppurative inflammation
pus = neutrophils (PMNs)
What do neutrophils do
they are first to arrive
phagocytosis
release toxic oxidative substances (ROS) to kill bacteria
release cytokines for recruitment
What is a disadvantage of ROS
they also damage host tissue
sustained inflammation
This is a virulence factor of S. aureus that blocks phagocytosis
polysaccharide capsule
This is a virulence factor of S. aureus that blocks antibody function
Protein A
This is a virulence factor of S. aureus that pop PMNs (lyse neutrophils)
pore-forming toxin
This is a specific toxin that is very toxic to PMNs
panton-valentine leukocidin
produced a lot by MRSA
This disease causes the layers of the epidermis to separate; caused by exfoliative toxins A and B
staphylococcal scaled skin syndrome
SSSS
What are exfoliative toxins
proteases with high-specifitiy for desmosomal proteins in the skin
TSST-1 (toxic shock syndrome toxin) is a what
superantigen
Superantigens cause what
an unregulated inflammatory response by activating high numbers of CD4 T cells
What cytokines are released that influence TSS symptoms
IL-1; fever
TNF-α and β; hypertension and capillary leakage
IFN-γ, IL-2; rash
With an intoxication, not an infection, of staph, what occurs
the toxin is pre-formed in contaminated unrefridgerated food (food poisoning)
Many strains of S. aureus secrete what
enterotoxins (A, B, C, D, E)
superantigens as enterotoxins cause what
intense paristalsis
What is special about the enterotoxin in food poisioning
It is heat stable
cooking the food will kill the bacteria, but no the toxin that has formed
These are penicillin binding proteins (PBP) that make the cross links in peptidoglycan
transpeptidsaes
transglycosylases
β-lactam antimicrobial agents are inhibitory substrates for what
PBPs
penicillin binds to the protein and inhibits cell wall formation
What are the two types of S. aureus that deal with the penicillin family
methicillin susceptible S. aureus (MSSA)
methicillin resistant S. aureus (MRSA)
What extra PBP is found in MRSA
PBP2a
There is prevalent resistance of what is S. aureus
β-lactam
True or False
MRSA frequently carry resistance genes to other drug classes
True!
This is used to treat MRSA, or presumed MRSA; although cases of resistant S. aureus have been reported via enterococcus faecium conjugative transposon
vancomycin
What makes MRSE so epidemiologically active
In some US regions, 50% of SA infections are MRSA
it is persistent, 21% still carry 4 years post diagnosis
True or False
MRSA is more statistically common in the population than in healthcare and professionals
False 1% of the population, 5-15% in healthcare, etc.
