bacteria: part 4 Flashcards
List the common virulence features for bacteria
Diverse secretion systems, Flagella (movement, attachment), Pili (important adherence factors), Capsule (protect against phagocytosis) i.e. Streptococcus pneumoniae ,Endospores (metabolically dormant forms of bacteria) heat, cold, desiccation and chemical resistant i.e. Bacillus sp. and Clostridium sp. Biofilms Exotoxin Endotoxin
Outline pyrogenic exotoxins
Stimulate cytokine release Staphylcoccus aureus or Streptococcus pyogenes
What is seen on the lipid bilayer of
On the lipid bilayer of gram negative bacteria, we see LPS and sugars – these are endotoxins
What can happen if lots of the LPS is shed
Then it can cause endotoxic shock Normally shed in steady amounts
Composition of shiga toxin
have an AB5 subunit composition Subunit a (StxA) is non-covalently associated with a pentamer of protein B (StxB).
Why is shiga toxin a mobile genetic element
Shiga toxins are encoded on a bacteriophage highly mobile genetic elements and contributes to horizontal gene transfer Toxins are highly expressed when the lytic cycle of the phage is activated (so that the gene can be taken up by lots of E coli)
Funciton of AAF
Allows binding to enterocytes AND allows binding to eachother to make biofim
Give example of BACTERIAL resp tract infections
Legionnaires’ disease (legionellosis) Legionella pneumophila (Gram -) Tuberculosis Mycobacterium tuberculosis (Gram +)
Where is legionella pneumophilia commonly found and what is the route of infection
Lives in amoeba in ponds, lakes, air conditioning units Infection route: inhalation of contaminated aerosols
What cells are affected in humans by legionella pneumophilia
In humans L. pneumophila will infect and grow in alveolar macrophages Human infection is “dead end” for bacteria – the bacteria can’t survive here on
What virulence factor is involved in L pneumophilia
Type IV secretion system There is a large protein spanning the 2 cell membranes and cell wall allows the bacteria to secrete effector proteins inside to out They are able to survive and replicate in macrophage vacuoles, because it can release special virulence factors due to the type IV system, and
Why is TB difficult to treat
Because it is grouped with gram +ve bacteria, but it has a very different cell wall Lots of lipids attached to the cell wall
What bugs cause gonorrhoea and syphilis
(Neisseria gonorrhoeae) and (Treponema pallidum) for syph
How can you acquire a Campylobacter sp. mostly C. jejuni infectin
Infection most likely through undercooked poultry
What is the virulence associated with salmonella sp
Type III secretion systems encoded on pathogenicity islands (SPI)
