pathogenicity
the ability to cause disease by overcoming host defenses
virulence
the degree of pathogenicity
what are the 3 portals of entry for a microbe
#NAME?
mucous membrane entry
-respiratory tract (easiest and most frequent)
-gastrointestinal tract (food, water, fingers; most die due to stomach acid, bile, enzymes; eliminated in feces)
-genitourinary tract (sexually contracted diseases)
skin
#NAME?
parenteral route
deposited directly into tissues when barriers are penetrated
punctures, bites, injections, cuts, wounds, surgery, skin splits
ID50
infectious dose for 50% of a sample population
-measures virulence of a microbe
LD50
lethal dose for 50% of a sample population
-measures potency of a toxin
adherance
a process in which all pathogens attach to host tissues at the portal entry
what are the 2 methods of adherance
1. adhesions on the pathogen bind to receptors on the host cells
2. biofilms
why do most pathogens invade host tissues
to cause disease
what are the factors that contribute to invasion of a host
#NAME?
describe a capsule
#NAME?
M protein
#NAME?
Opa Protein
#NAME?
waxy lipid (mycolic acid)
#NAME?
coagulase
#NAME?
bacterial kinases
#NAME?
hyaluronidase
#NAME?
collagenase
#NAME?
IgA protease
#NAME?
adaptive community
specific defensive response of the body to an infection or to antigens
antibodies
bind an antigen and destroy or inactivate it
at the beginning of an infection, what prevents the immune response from being useful
antigenic variation
when are antibodies produced
when there is an infection
Invasions
surface proteins produced by bacteria that rearrange actin filaments of the cytoskeleton
some cells use actin to move from one cell to the next
cytoskeleton
the movers are shapers in the cell
how does membrane ruffling occur
disruption of the cytoskeleton of the host cell
what are ways that a pathogen can cause damage if it is able to overcome the host defense
-using the host's nutrients
-causing direct damage at the site of an infection
-producing toxins that are transported to sites distant to the infection
-inducing hypersensitivity reactions
siderophores
proteins secreted by pathogens that bind iron more tightly than host cells
iron is required for most pathogenic bacteria, and the concentration of free iron in the body is low because of all the binding of it with proteins
describe direct cell damage
#NAME?
toxins
poisonous substances produced by microbes
toxigenicity
ability of a microbe to produce a toxin
toxemia
toxin in the host's blood
intoxications
presence of toxin without microbial growth
what is the type of toxin based off of
the toxins position in the cell
exotoxins
toxic substances released outside of the cell
(usually waste from metabolism and generally gram positive bacteria)
endotoxins
toxins composed of lipids that are part of the cell wall
(typically gram negative, the endotoxins are part of the phospholipid membrane and are liberated when the bacteria dies)
describe the protein exotoxins that are secreted by cells
#NAME?
antitoxins
antibodies against specific exotoxins
toxoids
inactivated exotoxins used in vaccines
what do A-B toxins contain
1. an enzyme component (A part)
2. a binding component (B part)
what are the 3 types of exotoxins
1. membrane-disrupting toxins
2. superantigens
3. genotoxins
membrane disrupting toxins
lyse host cells by disrupting plasma membranes
-form protein channels in membrane
-disrupt phospholipid portion of membrane
-contribute to virulence by killing host cells
leukocidins
kill phagocytic leukocytes
hemolysins
kill erythrocytes by forming protein channels
streptolysins
hemolysins produced by streptococci
superantigens
cause an intense immune response due to release of high levels of cytokines from host cells (T cells)
causes symptoms of fever, nausea, vomiting, diarrhea, shock, and death
genotoxins
damage DNA causing mutations disrupting cell division, and leading to cancer
cytokine
a small protein released from human cells that regulates the immune response and may induce fever, pain, or T cell proliferation
Lipid A
portion of lipopolysaccharides of gram-negative bacteria
when are endotoxins released
during bacterial multiplication and when gram-negative bacteria die and the cells undergo lysis
-stimulate macrophages to release cytokines
-at high levels cytokines are toxic
-cause blood clots
sepsis
presence of a toxin or bacteria in blood and tissue
septic shock
sudden drop in blood pressure induced by bacterial toxins
plasmids
may carry genes for toxins, antibiotic resistance, virulence factors, and enzymes
lysogenic conversion
changes characteristics of a microbe due to incorporation of a bacteriophage into the chromosome (prophage)
what are the pathogenic properties of viruses
#NAME?
cytopathic effects
visible effects of viral infection on a cell and vary depending on the virus
cytocidal effects
lead to cell death
used to diagnose viral infections
non-cytocidal effects
lead to cell damage but not death
mycotoxins
produced by mushrooms and are neurotoxic
portals of exit
allows the spread of the pathogen through a population
what are the portals of exit
respiratory tract
gastrointestinal tract
genitourinary tract
skin or wound infections
blood