microbiology: virulence factors
DESCRIPTION
Microbiology: Virulence Factors 1. Adhesion Factors 2. Extracellular Enzymes 3. Toxins 4. Antiphagocytic FactorsTRANSCRIPT
Chapter 3
Microbial Diseases
Jenna Lee Q. Valencia, RPh, BSCPS
Department of Pharmacy
School on Natural Sciences
Saint Louis University
Microbial DiseasesPathogenicity
Virulence
A. VIRULENCE
FACTORS
1. Adhesion FactorsSpecialized structures or
proteinsEnables microorganisms to
attach themselves to proteins
Ligand
2. Extracellular EnzymesMany pathogens secrete
enzymes that enable them to: Dissolve structural chemicals in the
body Maintain an infection Invade further Avoid body defenses.
a. Hyaluronidase“Spreading Factor”Digests hyaluronic acid
b. CollagenaseBreaks down collagen
c. CoagulaseCoagulates blood proteinsProviding a “hiding place” for
bacteria within a clot.
d. KinasesSuch as staphylokinase and
streptokinase Digests blood clots
e. Ig A ProteasesSplit Ig A at specific bondsInactivates Ab activity
f. NeuraminidaseProduced by intestinal
pathogensDegrades neuraminic acid
3. ToxinsChemicals produced by
pathogens that either harm tissues or trigger host immune responses that cause damage.
3. ToxinsTwo types of Toxins:
a. Exotoxin b. Endotoxin
a. ExotoxinsA-B Toxins
Cytotoxins
ExotoxinsNeurotoxin
Enterotoxin
Superantigens
Examples of Exotoxins
Diphtheria ToxinCorynebacterium
diphtheriae
Inhibits protein synthesis in eukaryotic cells
Erythrogenic ToxinsSuperantigens Damage the
plasma membranes of blood capillaries
Botulinum ToxinClostridium
botulinumA-B neurotoxininhibits the
release of acetylcholine
Tetanus ToxinClostridium
tetaniAKA:
TetanospasminA-B Neurotoxin
Vibrio EnterotoxinVibrio
choleraeAKA: Cholera
toxinA-B
enterotoxin
b. EndotoxinsGram negative bacteriaLipid portion of the outer
membraneAKA: Lipid A
4. Antiphagocytic Factors
CapsulesAntiphagocytic Chemicals
CapsulesComposed of chemicals that
are normally found in the body
Slippery
Antiphagocytic Chemicals
Chemicals that prevent the fusion of lysosomes with phagocytic vesicles