Lecture 13/14 Pathogenesis Flashcards
opportunistic pathogen
part of normal flora that causes disease when it has gained access to other tissue sites or host is immune compromised
pathogenicity
ability to cause disease
zoonoses
infections passed from animal to human
natural environmental location where the pathogen normally resides
animate or inanimate
reservoir
organisms that spread disease from one host to another
vector
infectious disease
infection with viruses, bacteria, fungi, protozoa, and helminths
incubation period
period after pathogen entry, before signs and symptoms
prodromal stage
onset of signs and symptoms
not clear enough for diagnosis
period of illness
stage where disease is most severe, signs and symptoms develop
convalescence
signs and symptoms begin to disappear
course of infection
- incubation period
- prodromal stage
- period of illness
- convalescence
a pathogen must ____ to cause disease
contact a host AND survive within it
3 requirements for pathogen to survive
- suitable environment
- source of nutrients (in competition with host cells)
- protection from harmful elements
virulence factors
allows a pathogen to outcompete host cells and resist their defenses
survival strategies of a pathogen (5)
adhesions enzymes toxins invasions autoinducers
virulence
degree or intensity of a pathogen
determined by pathogen’s ability to survive outside host
determines the degree to which the pathogen causes damage, invasion, infectivity
virulence factors
more dependence on host = (more/less) virulent
less
portal of entry
usually skin, respiratory, gastrointestinal, urogenital systems, or conductive of eye
parenteral route (break in barrier)
what are adherence structures?
pili or timbre that bind to complementary receptor sites on host cell surface
ligands
which glycocalyx ligand bind to receptors for adherence
s. mutans
fimbrae are ligands used by which bacteria for adherence
e. coli
s. pyogenes use which ligands
M protein
bacteremia
presence of viable bacteria in the blood
septicemia
pathogens or their toxins in the blood
disease that results from entry of specific preformed toxin into host
intoxication
ex. tetanus toxin
condition caused by toxins in the blood of host
toxemia
soluble, heat labile proteins
exotoxins
source of exotoxins
mostly gram +
metabolic products of exotoxins
by products of growing cell
are exotoxins neutralized by antitoxins?
yes
corynebacterium diphtheriae exotoxin
A-B toxin
+ lysogeny
strep pyogenes exotoxin
membrane disrupting ERYTHROGENIC toxin
scarlett fever
+ lysogeny
Clostridium botulinum exotoxin
a-b toxin
neurotoxin
+ lysogeny
C. tetani exotoxin
A-B toxin
neurotoxin
Vibrio cholerae exotoxin
A-B toxin
neurotoxin
Staphylococcus aureus exotoxin
superantigen
+ lysogeny
AB exotoxins
composed of two subunits (A and B)
specific host site exotoxins
membrane disrupting exotoxins
superantigens
Which part of the AB exotoxin is responsible for the toxic effect?
A subunit
Which part of the AB exotoxin is responsible for binding to specific target cell?
B subunit
superantigens
causes the T cells to over expresses and release cytokines
results in failure of multiple host organs allowing time for microbe to disseminate
parenteral route
pathogens that come into the skin, break thru barrier defenses
i.e. acne hasn’t penetrated, actually entering in thru barrier defenses
Infectious dose is indicated by
ID50
if a disease is very infectious it will have a ____ ID50
LOW
opposite of ea. other
what enzyme coagulates fibrinogen in plasma
coagulase
s. aureus
lyses erythrocytes
makes iron available
hemolysis
staph, strep, e. coli, c. perfringins
Leukocidins
pore forming exotoxin
kills leukocytes
causes degranulation of lysosomes of leukocytes
M protein
s. pyogenes
important for adherence and also helps cells evade phagocytosis
capsules
makes bacteria sticky to membranes
coat to avoid phagocytosis
invasins
allow bacteria to get inside cell
e. coli penetrate cells for example
proteolytic enzyme that allows a living organism to hydrolyse gelatin
gelatinase
collagenase
hydrolyzes collagen
hyaluronidase
hydrolyzes hyaluronic acid of ECM
allow pathogen passage inside cell
what produces endotoxins?
Gram -
what type of toxins cause fever?
endotoxins
which toxins are heat stable?
endotoxins
lipids
are AB toxins used by bacteria to adhere to things?
NO
the B subunit allows for binding and entry into host cell by A, but they are not used for adherence
M protein
resist phagocytosis (s. pyrogens)
Opa protein
inhibits T helper cells
N. gonorrhoeae
Mycolic acid
registry digestion and Ab resistant due to presence of mycolic acid in membrane
Mycobacterium tuberculosis
other ways to resist host cell defense
actin tail for propulsion (rickettsia, shigella)
formation of capsules to prevent phagocytosis
production of decoy proteins to bind to neutralizing Abs
enzyme secretion
Ig proteases
destroys IgA antibodies
Kinases
digests fibrin clots
coagulase
coagulates fibrinogen
infection v. intoxication
infection is when live bacteria establish themselves and grow then cause disease
intoxication is illness from presence of harmful toxins of bacteria
