chapter 11 mechanisms of pathogenicity (diana's version) Flashcards
how do micoorganisms enter a host
(in other words)-> what does it mean?
how an organism can makes us sick
true or false.
Because to be able cause an infection, absolutely fundamental for a virus to enter the body
True
True or false.
germs must first penetrate host defenses in order to damage tissues and go on to cause disease?
true
How do microorganisms enter a host ?
name the three
1.Mucous membranes
2.Skin
3.Parenteral Route
Mucous membranes :
what are the (3) subgroups
1) respiratory tract
2) gastrointestinal tract
3)genitourinary tract
Respiratory Tract:
the most common portal of entry
microbes are inhaled into the nose or the mouth
example : influenza, colds
true or false.
(respiratory tract)
we breathe about 12 times per min, exchange 500 mL o air imagine ow much air is contaminated you are taking in every breathe these infection particle are going to be taken by this route
true`
Sometimes we often get diarrahea, and vomiting they are characteristics of pathogen that have taken this portal entry
gastrointestinal tract
describe the gastrointestinal tract:
characteristics
germs enter in food or water
most are destroyed by the acid of the stomach or the bile of intestine
some such as vibrio cholerae can survive these conditions
rather breathe air in, through the ingestion of food and water
- this means that infectious agents will need to be represent within the food and water
-if you cook food properly, sterile the water, wash your apple properly, refrigerate properly
the likehood of____ being infected is reduced
this the example of gastrointestinal tract
this is the same tract in males because of the fact that uretha is being used
genitourinary tract
describe the characteristics of genitourinary tract
sexually transmitted infections
some pathogens require a broken mucous membrane
for example : a cut or micro-abrasion
other organisms can penetrate unbroken membranes
conjuctiva: the membrane covering the eye
what does conjuctiva
the membrane covering the eye
the membrane covering the eye
conjuctiva
can you expand on the term “cut or microabrasion”
normal intact barrier is not something they can bypast- but if they are natural problems they can basically weasle there way in that
inflammation of the covering of the eye sharing droplets, towel despite the fact that anatomy of the eye is perfectly intact
conjuctiva
describe how microorganisms enter a host
skin
unbroken skin is impenetrable by most microbes
- some microbes can gain access through hair follicles
-other microorganisms require a wound for entry
-some fungi grow on the skin, not needing to enter through skin breaches
true or false.
skin does not have the microorganisms past, because it is very strong
true
true or false.
60 layers of epithelium part of your epidemic, organisms have challenging time because of the tight junctions between them
true
sebaceous gland produces
sebum oil
oil is going to be _____ it’s waxy, not penetrable for water, any bugs can feed in order to facilitate in reproduction
hydrophobic
describe what “some fungi grow on the skin itself, not needing to enter through skin breaches
opening can allow to get further infection fungi actually have the capacity to grow on the surface of the skin (athelete’s foot)- ringworm right in the surface (that is fungus)
the fact that fungus is eukaryotic it is not ideal for oral antibiotic , rather treat with cream, so you are only putting it on top of the structure
tinea
pokes all the way through a defensive layer, and inoculates the tissues underneath
parental route
describe what parenteral route:
microbes deposited directly into tissues when skin or membranes are broken
example : a tick bite can introduce bacteria into the host, lyme disease
example : intravenous injection with a contaminated syringe, HIV
parenteral therapy as oppose to oral therapy and put them into your mouth
helps you deal with antibiotics that cannot cross the line of stomach
intervenous
true or false.
It is not just the quantity, have to consider the bacteria itself
true
the number of microbes introduced is important
-if two microbes enter the body immune system with fight them off easily and prevent disease
-the likelihood of disease occurring increases with the number of microbes introduced increases
The virulence of microbe may be expressed numerically :
i) infectious dose
2)potency of a toxin
the number tells you the danger, allows us to recognize how worse this bug to the other bug just given in the example
infectious dose
AGAIN just because something come inside your body, does not mean you are infected
describe what infectious dose mean
this is the amount of bacteria required to cause disease 50% of the population
example of infectious dose : bacillus anthracis
-enters through a cut in a skin in the ID50 is
-enters via inhalation the ID50 is
-enters via ingestion the ID50
10-20 endospores
10,000-20,000 endospores
250,000-1,000,000 endospores
ID50 is referring to what?
referring to how many organisms need to come in via initial inoculation in order to come in infection
this allows us to recognize how worse this bug is to the other bug.
infectious dose
Describe what potency of a toxin:
is something that’s able to kill
-expressed as the lethal dose
-the LD50 kills 50% of the infected population
mechanisms of pathogenicity
1) adherence
surface molecules that allow a pathogen to stick to the surface
they often stick to specific receptors on the host cell surface
mechanisms of pathogenecity of adherence
name some examples
example : fimbriae or glycocalyx of abcteria
example : viral proteins that allow adherence to specific host cell proteins
analogy: could be like me sticking my key to the door
- suction cup to the window
adherance
mechanisms of pathogenicity:
invasiveness
the ability of a pathogen to invade and multiply in healthy tissues
- there are two types of molecules to promote invasiveness
they are extracellular enzymes
invasins
enzymes that cut things ( outside ) have the opportunity to act :
extracellular enzymes (exoenzymes)
describe the characteristics of extracellular enzymes (exoenzymes):
these enzymes erode the surface of host cells and damage tissues
i) hemolysin : destroys red blood cells
ii)fibrinolysis: degrades fibrin coats
iii) collagenase : degrades connective tissues
iv) cogulase : promotes blood coats around the bacterial cell
true or false .
extracellular enzymes (exoenzymes)
products of degradation are used as a source of food and to protect the microbe form host defenses
true
describe invasins :
membranes becomes flexible due to cytoskeleton rearrangment
surface proteins that cause the rearrangments of the host cell cytoskeleteon
the forces the host cell to take in the bacterium
the bacterial cell is protected from the host defenses inside of the cell
gets released in the outside and comes in the red blood cell , the outcome is the red blood cell will lysis
hemolysin
done in your body to keep the bacteria from spreading, they are going to be trapped if they are able to produce _______ cause clot to dissolve then organism can reach other location
fibrinolysin
degrades connective tissue, specific for cutting collagen
collagenase
____ is the most abundant tissue- it will literally cut
collagen
Describe what coagulase mean:
promotes blood clots around the bacterial cell`
rather than breaking the form clots you made , it forces blood formation- he is inside the clot-immune system
cannot see him-outcome he is protective
coagulase
mechanisms of pathogenicity:
Bacterial Toxins:
define what toxin mean
define what toxoid mean
Toxin: is a poisonous substance produced by a microorganism
Toxoids can be used as a vaccine
ex : DTaP vaccine consist of 3 toxoids : diptheria, pertussis, tetanus
Bacterial toxins:
Exotoxins:
give an example
These are toxins which are secreted from the bacteria
they are heat sensitive
they can be extremely toxic: some of the most lethal substances known
example : clostridium botulinum causes botulism
botulism toxin: 1 mg can kill 1,000,000 guinea pigs
this exotoxin can go into your diaphragm and cause you to die
clostridium botulinum
what are the categories of exotoxins
(3)
1.Neurotoxins
2.Enterotoxins
3.Cytotoxins
Neurotoxins (what are the subgroups)
botulinum toxin
tetanus toxin
what is neurotoxin and explain what botulinum toxin
interfere with nerve impulses
botulinum toxin : causes flaccid paralysis
produced by clostridium botulinum
muscles permanently relax
the heart stops beating and breathing stops
what does tetanus toxin mean:
causes rigid paralysis
produced by clostridum tetani
uncountable muscle contraction (spasms) : results in lockjaw
death usually occurs due to spasms of the respiratory muscles
stays relax and no room to expand
flaccid paralysis
same idea of botulinum toxin but opposite effect
do not have the capacity to relax muscle
collectively a disorder we call lockjaw
die of suffocation because the respiratory is locked
tetanus toxin
describe the characteristics of enterotoxins
interfere with salt absorption in the small intestine
- to counteract the high salt concentration in the intestine the cells pump out water
-causes watery disrrhea
example) montezumas revenge (E.coli), cholera (vibrio cholera)
describe what cytotoxins means
kill cells
these interfere with protein synthesis, killing all types of cells
example : diphtheria toxin causes respiratory illness
part of the outer membrane of gram negative bacteria
lipopolysaccharide (LPS)
endotoxin
name some characteristics of endotoxins
does not cause any problems when it is embedded in the membrane
endotoxin (LPS) is released when the bacterium
dies resulting in worsening of symptoms
can cause fever ,hemorrhaging, and shock (sudden decrease in blood pressure)
True or false.
Endotoxin is not as potent as exotoxin and much more is needed to cause symptoms
true
what would be an example of endotoxin? and describe the characteristics along with it
salmonellosis (salmonella enterica)
food poisoning due to millions of dead bacteria
the symptoms are causes by the endotoxin
antibiotic treatment may do more harm than good
___ can do more harm than good because it aggressively kill negative bugs releasing lots of endotoxin quickly
antibiotic
gram negative systemic infection can be best treated with what type of antibiotics and why?
bacteriostatic antibiotics, because it holds the number constant from replicating and immune system can clean up the mess more gently
comparing endotoxins and exotoxins
distinguish what the differences are between the two
exotoxins:
Proteins
released outside of the cell
extremely toxic and often lthal
endototoxins:
lipopolysaccharides (LPS)
only released when bacteria dies
not as toxic , usually not lethal
this is attached to the outside membrane and only gets released when it dies, and toxin portion is the lipid A or the L in the LPS.What is it referred to as?
endotoxin
Viral infections are …
mechanisms for evading defenses:
viruses invade and grow inside of the cells
components of the immune system cannot reach them
visible effects of vital infection and disruption of cell processes
cytopathic effects
what is an example of cytopathic effect
herpex simplex virus stops host cell division
what is HSV I
HSV II
HSV I = oral herpes
HSV II= genital herpes
name more characteristics of cytopathic effects:
destruction of intracellular structures occurs
the virus can form inclusion bodies which consists of viral parts (capsomeres)
giant cell formation : several infected cells fuse to form one giant cell example : caused by colds
infection often results in host cell death
describe what destruction of intracellular structures mean during cytopathic effects?
mitochondrial destruction, ribosomes, eukaryotic cell
if it’s a naked virus lysis of release envelope happens eventually
often results in host cell death
