staphylococci Flashcards
Gram positive Cocci has what shape
spherical
Gram positive Cocci have an absence of
endospores
Catalase positive genera
staphylococcus
micrococcus
Catalase negative genera
streptococcus
enterococcus
Anaerobic gram positive cocci
properties of staphylococcus
nonmotile (cant move itself)
Facultatively anaerobic (can switch to not using oxygen)
halotolerant = living in conditions of high salinity
Temperature range 18-40*c
simple media
where is staphylococcus found
skin and mucous membranes
What is the most virulent staphylococcus
s. aureus
- only species to produce enzyme coagulase
- can survive well in the enviroment and is easily spread from person to person
what is staphyloccus golden
produces carotenoid pigments
staph aureus: Virulence factors
Structural components
toxins
enzymes
Staph aureus: structural components
capsule
- loose fitting slime layer
Seen occasionally in vitro
inhibits:
- Chemotaxis
- phagocytosis
facilitates adherence
peptidoglycan layer
Teichoic acids aid attachment to host via fibronectin receptors
Staph aureus: Structural components:
Protein A ….
Coats surface
binds Fc receptors of IgG1,2 and 4
Staph aureus: Structural components:
extracellular protein A…
Binds antibodies
forms immune complexes
Staph aureus: Structural components:
Bound coagulase - clumping factors
Binds fibrinogen and converts to fibrin
Staph aureus: Structural components:
Cytoplasmic membrane:
Transport and anchorage
Staphylococcal toxins
Cytolytic
- membrane damaging toxins
Alpha, beta, delta, gamma and leukocidin
what cells are staphylococcal toxic too
leukocytes
erythrocytes
macrophages
platelets
fibroblasts
Staphylococcal exfoliative toxins
names = exfoliatin, epidermolytic toxin
causes = scales skin syndrome
characterised by exfoliative dermatitis
two distinct forms, A and B , either can produce disease
seen mostly in young children
toxic shock syndrome toxin ! (TSSTS1)
- Fever
- Hypotension
- Rash
- Followed by desquamation
- Multi organ system involvement
- Toxin secreted during growth
how many serologically distinct exotoxins
5
named from A to E
Staphylococcal Enterotoxins are resistant too
hydrolysis by gastric and jejunal enzymes.
Staphylococcal Enterotoxins has a percentage of strains that produce what
30-50% produce enterotoxin