Negative Associations Flashcards
what are the three steps in the infection process
adhesion
invasion
multiplication
what is a bacterial capsule
a sticky outer layer that can help the bacteria attach to host tissue or protect the bacteria from defences. The capsule is composed of D-gluatamate amino-acids
what are adhesins
adhesins are various apendages that bacteria have that allow them to attach to specific receptor molecules. The bacteria can selectively infect certain cells and tissues.
what is virulence
the relative ability of a bacteria to cause disease
what is pathogenicity
the ability of the pathogen to inflict damage on the host.
what are the three categories of exotoxins
AB toxins
cytolytic toxins
superantigen toxins
what are AB toxins
a class of toxins containing two subunits. The B subunit binds to the cell membrane which allows the A subunit to pass through and damage the cell.
what are cytolitic toxins
they damage the cell membrane causing cell lysis and death. It is easy to detect cytolytic toxins using blood agar plates.
an example CT toxins are streptolysin O produced by streptococci bacteria
what are superantigen exotoxins
they work by stimulating large numbers of immune cells causing inflamation and tissue damage. staphylococcus aureus produces superantigen toxins
what are endotoxins
toxic lipopolysaccharides in the membrane of gram negative bacteria. They are only secreted on cell death when they lyse.
what is sepsis
the bodies overwhelming and life threatening response to infection, usually caused by bacteria.
what is a persistent infection
when a virus infects a cell, it releases small amounts of the virus so the infected cell doesn’t fully lyse and die
what is a latent infection
a delay between viral infection and host cell lysis e.g. herpes
what is HPV
one of few viruses that can cause cancer. HPV causes cervical and throat cancer.
what is HIV
a retrovirus that infects the T-helper cells and macrophages of the immune system. It binds to CD4 receptors in lymphocytes
