Lecture 15 - Microbial Mechanisms of Pathogenicity Flashcards
Describe the difference and relationship between INFECTION and DISEASE
Infection occurs when a pathogen gains access to a part of the body where it shouldn’t be or in abnormally high numbers and can cause disease once the pathogen causes cellular damage
What is the most important determinant of a disease outcome?
the host’s immune system
pathogenicity
the ability of a microbe to cause disease
virulence
the relative degree of pathogenicity
(the relative degree of the ability of a microbe to cause disease)
Name the 4 Main Steps that Must Occur for a Pathogen to Cause Disease
1 - Pathogen must gain access to the host through a portal of entry
2 - Pathogen must be able to adhere/stick to the body
3 - Pathogen must be able to penetrate and evade host’s immune defenses
4 - Pathogen must damage the host’s tissues
Name 3 Portals of Entry Specific to Women
- Mammary Glands
- Vagina
- Placenta
List Common Portals of Entry
- eyes
- ears
- mouth
- nose
- broken skin
- urethra
- anus
mucous membranes
membranes lining body cavities that have an opening to the outside
(i.e. entire GI tract, urinary tract, bronchi)
Parental Route of Entry
when a break in the skin becomes a portal of entry for a microbe
(i.e. dog bite, insect bite, cut/scrape, contaminated needle)
Lethal Dose
the number of microbes it would take to kill half of the exposed population
Infective Dose
The dose that will cause disease in 50% of the population
ID
Infective Dose
LD
Lethal Dose
adhesin
found on the surface of bacterial cell walls which helps them adhere to the host’s membranes
- this aids the bacteria in resisting the normal flow of body fluids so that it can cause an infection
Can staphylococcus aureus form a capsule?
Yes
phagocytosis
cell eating
Name 2 Components of a Cell Wall that are Anti-Phagocytic
- LPS (Lipopolysaccharide)
- Mycolic Acid
LPS
Lipopolysaccharide
Where is LPS (Lipopolysaccharide) Found?
the cell walls of Gram-Negative bacteria
Name a Genus of Bacteria that Produces Mycolic Acid
Mycoplasma
coagulase
an enzyme produced by some bacteria causing blood to clot
fibrinolysin
an enzyme secreted by some bacteria to break down clots
streptokinase
a type of fibrinolysin
hyaluronidase
an enzyme secreted by some bacteria to break down hyaluronic acid in the body
collagenase
an enzyme secreted by some bacteria to break down collagen
IgA protease
an enzyme secreted by some bacteria to destroy IgA antibodies
antigen
foreign substance that induces an immune response
antigenic variation
occurs when an antigen mutates in such a way that the body cannot readily recognize it and initate an effective immune response rapidly
How is it that viruses mutate so well?
RNA viruses are replicated by RNA Polymerase which is fairly error-prone. When RNA Polymerase makes a mistake it can change the RNA in such a way that it may code for different spike proteins
Is COVID an RNA or DNA Virus?
RNA
Membrane Ruffling
A method in which bacteria can pass into a huaman cell.
siderophore
Molelcule secreted by bacteria that attach to Iron (Fe). The bacteria then reabsorb the siderophore attached to the Fe.
LPS contains which endotoxin?
Lipid A
Name two categories of Microbial Toxins
Endotoxins & Exotoxins
Where are the genes for most exotoxins found?
Plasmids or Prophages
Toxin Produced by Streptococcus pyogenes
Erythrogenic Toxin
Toxin Produced by Clostridium botulinum
Botulinum Toxin
Toxin Produced by Clostridium Tetani
Tetanus Toxin AKA Tetanospasmin
Neurotoxins
exotoxins that attack nerve cells
Enterotoxins
exotoxins that attack the intestines
Leukocidin
an exotoxin which attacks and kills WBCs by disrupting the cell membrane
-cide
to kill/destroy
leuk/o
white
WBC
White Blood Cells
Hemolysin
an exotoxin which destroys RBCs
RBC
Red Blood Cells
hemo-
blood
Gram-Negative Bacteria Stains
Pink
Gram-Positive Bacteria Stains
Purple
Is Clostridium geneus Gram-Positive or Negative?
Gram-Positive
Do Gram-Negatives have endotoxin in their cell walls?
Yes - Lipid A
pyrogen
fever-causing
Are Endotoxins pyrogens?
Yes
Are Exotoxins pyrogens?
Not necessarily
Idiopathic Miscarriages may be associated with _____.
Endotoxins
DIC
Disseminated Intravasular Coagulation
What is DIC (Disseminated Intravascular Coagulation)?
tissue death caused by endotoxins causing numerous little blood clots which block off capillaries and consequently cause tissue death
Hypersensitivity Reactions
immune responses that are more damaging than good (i.e. autoimmune reactions, transplant rejections, severe allergies)
describe the tell-telll symptoms of shingles
rash or blistery-sores generally presenting only on one half of the body
List a Few Pathogenic Properties of Fungi
- capsules
- production of toxins
- induction of hypersensitivity reactions
Which portal of exit on a person is most common?
Respiratory (i.e. coughing and sneezing)
