Chapter 8 - Bacteria Flashcards
where are adhesins found
on bacterium
where are receptors found
on host cell
what parts of gram negative bacteria interact with the host epithelial cells
bacterial proteins on the tips of fimbriae and/or pili interact with glycolipids and/or glycoproteins of host epithelial cells
what are intimins and what do they do
bacterial proteins at the cell surface
- interact with their own translocated intimin receptor (TIR)
what do gram positive bacteria often bind
fibronectin which binds to integrins
what are fibronectin binding proteins
subclass of a large family of bacterial adhesins referred to as Microbial Surface Components Recognizing Adhesive Matrix Molecules or MSCRAMMS
what are MSCRAMM targets
fibrinogen and collagen
what causes greater incidence of pneumonias
gram negative bacteria
when individuals are in poor health and fibronectin deficient the balance shifts in favor of_____
gram negatives
what do serine rich repeat proteins (SRRPs) do and what bacteria are they associated with
- extend a unique non-repeat domain that mediates adhesion
- gram-positive bacteria
what does the NR domain bind
sialic acid moieties, keratin and other NR domains of a similar SRRP
what are examples of sialic acid binding adhesins
oral infectious disease and endocarditis
what is C3a and what does it cause
anaphylatoxin (inducer of acute inflammation)
what is C3b and what is it a part of
an opsonin and part of C3 convertase and C5 convertase
what is C5a
a chemotactic protein for neutrophils and an anaphylatoxin
what are some microbial mechanisms to defend against complement
- addition of sialic acid to lipooligosaccharide inhibits complement fixation
- C3b peptidase cleaves the complement component into inactive fragments
- long chain smooth LPS limits access of the MAC to the organism surface
- polysaccharide capsule masks surface components that can activate complement via the alternate pathway
how do pathogens subvert phagocytosis
- inhibit phagocyte recruitment and function
-Cleave C5a so neutrophils are not attracted - increase cAMP to inhibitory levels
- leukocidins
- escaping ingestion
-survival inside phagocytes
what are leukocidins
enzymes that kill phagocytes
how do pathogens escape ingestion
-protein A
- expressed on bacterial cell surface
- binds Fc portion of IgG
- bound antibodies cannot act as opsonins
how do pathogens survive inside phagocytes
- inhibit lysosomal fusion with phagosome
- escape into the cytoplasm
- resist lysosomal enzymes
-inhibit phagocytes oxidative pathway
how do bacteria penetrate nonphagocytic host cells
stimulating host cell membrane protrusion
what are internalins and what do they interact with
- bacterial proteins at the cell surface
- interact with host E-cadherin
what are invasins and what do they interact with
- bacterial proteins at the cell surface
- interact with host integrins
how do bacteria transmit to other cells
actin dependent intracellular motility and intercellular spread
how are immune responses subverted
-immunosuppression
-superantigens
- changing antigenic coats
- proteolysis of antibodies
what do superantigens do
divert lymphocyte function
