Virulence Factors Flashcards
(34 cards)
is a causative agent of nosocomial infections due to living in biofilm
P. aeruginosa
bacteria grow in biofilms, in
which they are protected against disinfectants.
Workers in cooling towers, persons working in air
conditioned rooms and people taking a shower are
exposed to
Legionellosis
spreading factor. It is produced by streptococci, staphylococci and clostridia.
The enzyme attacks the interstitial cement (“ground substance”) of connective tissue
Hyaluronidase
produced by Cl. perfringens.
It breaks down collagen, the framework of muscles,
which facilitates gas gangrene due to these organisms.
Collagenase
produced by intestinal pathogens such as V. cholerae and Sh. dysenteriae. It degrades sialic acid, an intercellular cement of the epithelial cells of the intestinal mucosa.
Neuraminidase
Kinase enzymes convert inactive plasminogen to plasmin which digests fibrin and prevents clotting of the blood and allows more rapid diffusion of the infectious bacteria.
Streptokinase and staphylokinase
produced by Cl. perfringens, destroy (phosphatidyl choline) in cell membranes.
Lecithinases
produced by Cl. perfringens (i.e., alphatoxin), hydrolyze phospholipids in cell membranes by removal of polar head groups.
Phospholipases
produced by staphylococci (i.e., alphatoxin), streptococci (i.e., streptolysin) and various clostridia, that destroy red blood cells and other cells (i.e., phagocytes) by lysis.
Hemolysins
destroys both PML and macrophages.
Leukocidin
breaks down fat
Lipase
Coagulase, formed by S. aureus, is a cell-associated and diffusible enzyme that converts fibrinogen to fibrin which causes clotting.
Staphylococcal coagulase:
produced by N. gonorrhoeae, N. meningitidis, H. influenzae and S. Pneumoniae. It degrades the secretory IgA on mucous surfaces and thus eliminates protection of the host by antibody.
Immunoglobulin A (IgA) protease
survive by inhibiting
phagosome-lysosome fusion.
M. tuberculosis and Legionella
quickly escapes the phagosome into the cytoplasm
before phagosome-lysosome formation.
Listeria
- The genes are carried on plasmids or bacteriophages rather than chromosomes.
- Diffuse
- +/-
- toxoidable
- release during life cell
Exogenic
———- component binds,———enzymaically active
B
A
bind non-specifically, activate large
numbers of T cells which in turn release large amounts of
cytokines.
Superantigens
small proteins that regulate immune responses and in high
concentrations can cause many symptoms and signs: fever, nausea,
vomiting, diarrhea, shock and even death
Cytokines
secrete hemolysins that cause the
complete lysis of RBC’s
Beta Hemolytic Streptococci (exo)
preparations of exotoxins chemically treated to destroy their toxigenicity but retain their ability to elicit antibody formation in the body.
(Immunizes exotoxins)
Toxoid
-produced only by Gram-negative
bacteria and released only when bacteria lyze.
-lipopolysaccharide
of the outer membrane of Gram-negative bacteria;Lipid A
-@ bacterial chromosomes
-release upon cell lysis
Endotoxins
produces IL-1 and TNF → fever-shock
Macrophages
C3a and C5a→ release of mast cell
mediator as bradykinin→ vasodilatation and hypotension
Complement
