Microbial Mechanisms of Pathogenicity
How Pathogens Penetrate Host Defenses
Antigenic Variation
Antibodies
Antigens
Actin in cytoskeleton
To move
To penetrate
The production of toxins
Antitoxin
Toxoid
Toxemia
Toxigenicity
Enzymes
IgA proteases
Hyaluronidase
Kinases
Coagulase
Cell Wall Components
Mycolic acid
Opa-protein
Capsules
Haemophilus influenzae
Streptococcus pneumoniae
How Pathogens Damage Host Cells
Exotoxins
superantigens
membrane-disrupting toxins
lysis the host cells
Disrupting phospholipid bilayer
Making protein channels
A-B toxins
B-part (the binding)
A-part (enzyme)
Endotoxins
cytokines
Direct Damage
Produce waste products
Disrupt host cell function
Using the Host’s Nutrients
receptors
siderophores
How microorganisms enter & exit a host
Portals of Exit (the same as the portals of entry for a given microbe )
Adherence
M protein
Streptococcus pyogenes
Fimbriae
Escherichia coli
Glycocalyx
Streptococcus mutans
Numbers of Invading Microbes
ID50
LD50
The Preferred Portal of Entry
Bacillus anthracis
Subtopic
multiple portal of entry
Streptococci
inhaled
Salmonella typhi
swallowed
Portals of Entry
Parenteral route
njections
wounds
Skin
hair follicles
sweat gland ducts
Mucous membranes
respiratory tract
gastrointestinal tract
