Virulence Factors Flashcards
Which type of bacteria have Endo/Exo toxins and why? (gram stain)
Positive - have exo only
Negative - have endo and exo - endo because they have heat stable lipopolysaccharides in protein outer membrane that gram pos bacteria doesn’t have - these release into host circulation on bacteriolysis and affect host - septic shock.
What 4 categories of exotoxin are there? What do they do?
1) AB toxins - cells secrete toxic proteins with 2 parts (active and binding)
2) Superantigens - bind to MHC-II molecules and recognised by CD4 T cells = interleukins and cytokines = septic shock
3) Enzymes - eg phosphlipases break down host cell membranes
4) Cytolytic - lyse host cells by disrupting cell membrane
What is a bacterial cell capsule?
Polysaccharide outer layer of some bacteria which acts as a virulence factor as prevents phagocytosis
What do pili/fimbrae do?
Attach to surface
Are fimbrae in gram pos neg or both?
Only gram neg
What other role of fimbrae have?
Initiating biofilm formation
What is slime layer vs biofilm vs capsule?
Slime is disorganised ECM round bacteria that helps protect from phagocytes and helps adhere
Biofilm is made up of some types of slime
Capsule is a more rigid structure that helps prevent against phagocytosis
From the list of bacteria which 3 produce biofilm?
Staph aureus
Staph epidermis
E coli
How do you treat someone with a prosthetic with biofilm on it?
Have to remove it - antibiotics don’t kill biofilm
Which 5 from the list of bacteria have a capsule?
E coli Strep pyogenes Strep pneumoniae Neisseria meningitidis Haemophillus influenza
Which 3 have pili
Strep pneumoniae
Neisseria Meningitidis
Ecoli
Which 2 have flagella
Legionella Pneumophila
E coli
Which 2 have low/no virulence?
Strep viridians - relatively avirulent
Staph epidermis - low virulence
What are strep pyogenes 8 virulence factors?
Streptokinase M protein Adhesins Streptolysins O & S Hyaluronidase Exotoxin pyogenic --> superantigen DNAases Capsule - polysaccharide/hyaluronate
Diseases associated with super antigen production?
Rheumatic fever
Scarlet fever
Toxic Shock Syndrome
Infective Endocarditis
