Flashcards in Microbiology Deck (128)
What is virulence?
the capacity of a microbe to cause damage to the host
What are virulence ffactors?
The factors responsible for the variation in virulence within and between species
What is adhesin?
enables binding of the organism to host tissue
What is invasin
enabled the organism to invade a host cell/tissue
what is impedin?
enables the organims to avoid host defense mechanisms
What is aggressin?
causes damage to the host directly
What is modulin?
induces damage to the host indirectly
Where is S.aureus found on the body?
anterior nares and perineum
What skin diesases can Staph. aureus cause?
rash; folliculitis; carbuncle; impetigo; abscess; scalded skin syndrome
What do adhesins bind to?
extracellular matrix molecules that are present on cell surfaces
Give 2 examples of adhesins?
What disease does collagen-binding factor allow Staph. aureus to cause?
Do all Staph. aureus have all virulence factors?
What is the purpose of hte capsule?
a thick polysaccharide layer that allows bacteria to evade and hide from the immune system
What is a toxinoses?
It is a disease that isn't caused by the bacteria itself but by the toxin it produces
What is a superantigen?
Doesn't bind directly to MHC class 2 complex but binds outside conventional binding groove which causes a cytokine storm and inappropriate immune response
Give an example of a superantigen
What disease does TSST-1 cause?
Toxic Shock Syndrome
What are the symptoms of Toxic Shock Syndrome?
diffuse macular rash and desquamation
more than three organs involved
What does Panton- Valentine Leukocidin do?
specific toxicity for leukocytes so stop immune system working
What conditions is PVL associated with?
sepsis/ necrotising fasciitis
Why do antibiotics fail in the treatment of necrotising penumonia?
The toxin is causing the disease not the bacteria and the antibitocs do not target the toxin
gram positive cocci
What skin infections does streptococcus pyogenes cause?
impetigo, cellulitis, necrotising fasciitis
If a microbe causes beta haemolysis, what does this mean the bacteria can do?
produce a protein that can destroy RBCs
What proteins are involved in helping Strep. pyogenes in adhesion?
What superantigens cause Toxic shock like syndrome?
SpeB and SpeC
What allows both Staph. aureus and Strep. pyogenes to cause Toxic Shock?
Similar exo-proteins, common virulence factors and disease mechanisms
What is variation in disease and virulence the result of?
variation in genes