Staphylococci Flashcards
S. aureus appearance
Gram positive cocci, forms clusters, coagulase positive
Virulence factors
Biofilm, surface proteins that bind to collagen, fibronectin, ferritin, and secreted proteins.
Main virulence factor for Staph aureus? How does it work?
Protein A, binds to the Fc terminal of IgG inhibiting complement fixation and phagocytosis.
Main type of S. aureus pathology?
Abscess
How else (besides protein A) does S. aureus evade opsonization?
Polysaccharide capsule
What are more virulent, coagulase positive or coagulase negative staphylococci?
Coagulase positive (S. aureus) is more virulent than coagulase negative (S. epidermidis).
Toxin mediated staph pathogenesis
Toxic shock syndrome by TSST1, scalded skin syndrome, rapid onset food poisoning (preformed toxin).
Which toxic shock syndrome is more severe, group A strep or staph aureus?
Strep
How does Staphylococcus aureus adherence promote survival?
A polysaccharide web is created that is impermeable to antibodies and too big to phagocytose. Forms a slime layer that promotes seeding
Why do we have to treat a patient with a staph positive blood smear for 4 weeks, when we don’t really have to worry about a strep positive blood smear?
Because staph is really sticky and can (and will) land anywhere. If its in the blood, its already seeded into a colony.
Staph aureus skin infections
Abscess, impetigo, cellulitis, chalazion
Staph vs strep viridians endocarditis
Staph affects normal valves, and strep viridians affects damaged valves
Staph effects on bone and muscle
Can cause abscesses, osteomyelitis, and septic arthritis
Can staph cause pneumonia?
Yes, for people with ventilators. Staph is a common cause of hospital based infections.
T/F Staphylococcus aureus is a frequent cause of hospital based infections.
True
