12/4 Quiz Pathogenicity Flashcards
refers to a microbe’s ability to cause a disease
Microbial Pathogenicity (P)
P=NV/R
P=Pathogenicity
N = number
V = virulence
R = resistance
the greater the number of invading microbes,
the greater the chance that the microbe will overcome the host defenses
Host Resistance depends upon
innate 1st and 2nd lines of defense and a specific 3rd line of defense
(immune response)
the properties of a microbe that enhance pathogeniity
there are degrees of pathogenicity
Virulence
the microbe’s ability to to replicate rapidly
Invasiveness
Virulence
how well a microbe attaches to the host
- fimbriae? spikes? glycocalyx?
- are somewhat specific
Invasiveness
Virulence
- Enzymes
- Adapting/Utilizing vector to penetrate 1st line of defense
Promote Microbial Entry to Host Tissues
Invasiveness
Virulence
Produced by some fungi and digests the keratin in skin
Keratinase
Microbial Entry to Host Tissues
Invasiveness
Virulence
digests hyaluronic acid, intercellular “cementing” substance between surface cells
hyaluronidase
Microbial Entry to Host Tissues
Invasiveness
Virulence
enzyme that digests collagen, most common protein/CT in the body
Collagenase
Microbial Entry to Host Tissues
Invasiveness
Virulence
convert plasminogen into plasmin, an enzyme that breaks down blood clots
Streptokinase/Staphylokinase
Microbial Entry to Host Tissues
Invasiveness
Virulence
causes a web-like clot that impedes WBC movement
Coagulase
Microbial Inhibition of Phagocytosis
Invasiveness
Virulence
kills WBC
Leukocidin
Microbial Inhibition of Phagocytosis
Invasiveness
Virulence
mechanically interfere with phagocytosis
Fimbriae and Capsules
Microbial Inhibition of Phagocytosis
Invasiveness
Virulence
resistant cell walls may inhibit digestion by phagocytes
Fact.
bacterial are toxins that act as pores
- lyse red blood cells
- iron released from RBC’s appropriate for microbial use
- ALPHA’s cause partial hemolysis, leaving greenish ring around microbial colonies
- BETA’s cause complete hemolysis, leaving clear ring around micorbial colonies
Hemolysins
Acquisition of Host Resources
Invasiveness
Virulence
Viruses enter host cells and take over the resources and machinery of their hosts
Acquisition of Host Resources
Invasiveness
Virulence
Toxins disrupt the cell membrane or the internal activities of a cell
Toxigenicity
-are the lipid A part of te outer membrane of Gram-NEGATIVE bacteria
Endotoxins
Toxigenicity
-are relased when G- bacteria die
Endotoxins - Lipid A
Toxigenicity
are weak, nonspecific and CAUSE A FEVER
Endotoxins - Lipid A
Toxigenicity
Stimulate weak immunity
Endotoxins - Lipid A
Toxigenicity
Stable
- can’t be denatured and converted into toxoid
- can’t be used for immunizations
Endotoxins - Lipid A
Toxigenicity
associated with a few Gram+ and few G- bacteria
Exotoxins
Toxigenicity
are secreted
Exotoxins
Toxigenicity
polypeptide, unstable, powerful, do NOT tend to cause fever
Exotoxins
Toxigenicity
can be denatured and converted to TOXOID whhich can be used for immunization
Exotoxins
Toxigenicity
are highly specific
Exotoxins
Toxigenicity
attack the nervous system
Exotoxins - NEUROTOXINS
Toxigenicity
attack organs of the digestive tract
Exotoxins - ENTEROTOXINS
Toxigenicity
