Lecture 7+8+DLA Flashcards
what is a T-distribution
is a way of describing data that follow a bell curve
used for smaller sample sizes
the variance of the data is not known; estimated based on degrees of freedom (total number of observations minus 1)
lower probability to the center and more to the tails, which differs from the Z-distribution
T vs Z distribution?
T:
small sample size
estimate the confidence interval around the mean
the more degrees of freedom the closer it matches the Z distribution (roughly 30)
Z:
your confidence interval will be artificially precise
commensal vs pathogen
commensal is symbiotic and endogenous
pathogen is a true infection that comes from an outside source
can opportunistic in those with immuno-deficiency
what is the multi-step disease process?
- attachment and colonization
adhere and replicate - invasion and dissemination
penetrate the body - inflammation
peak of symptoms - convalescence
healing - resolution
eradication
how do flagella help with virulence?
Ex?
based in the cell wall and extend extracellularly
serve as motility
can help with attachment and penetrate mucous layers
Ex: salmonella
is recognized by the innate immune system
how does a capsule help with virulence
also known as the glycocalyx
Functions to help the organism resist
environmental and immunological insults
capsules are anti-phagocytic
high risk infection in those with asplenia
adhesions and virulence
Cell wall appendages that are important for attachment to host tissue or abiotic surfaces, such as catheters.
fimbriae are non specific binding; these are numerus but short, weak binding
pili- few but long, often have a receptor, strong binding
sex pili - play a role in horizontal gene transfer
secretion systems and virulence
type 3? Ex?
Secretion Systems are based in cell wall of bacteria to release of exotoxins, enzymes and effector proteins.
type 3 = acts as a “needle” to inject effector proteins into host and modifying host cellular characteristics
Ex: salmonella
endospores and virulence
ex?
formed during harsh environments; lack of nutrients
found in the soil and environment
highly resistant to desiccation due to the spore coat full of dipicolinic acid
Ex:
bacillus and clostridium
how do biofilms work?
- attach weakly with cell wall products to host tissue and abiotic features
- adhere tightly with irreversible adherins
- replicate and secrete into extracellular matrix
- Establish persistent biofilm, releasing top layers only
kinds of enzymes released by bacteria
enzymes are used to break down host tissue
promote evasion
protease = degrade protein Hyaluronidase = degrades hyaluronic acid in extracellular matrix Collagenase = degrades collagen in extracellular matrix
super-antigen (exotoxin)
Ex?
is secreted by bacteria from local infection
Toxin migrates to Lymph Nodes and locks antigen-presenting cell to T-helper cell
Non-specific activation leads to massive cytokine release, causing Toxic Shock
Ex. Staph aureus Toxic Shock Syndrome Toxin
cytotoxin (exotoxin)
Ex?
secreted by bacteria from local infection
forms pores in host cell membranes
localized inflammation and damage
Ex: staph aureus (α-toxin causes Beta-hemolysis pattern on Blood agar)
A/B type toxin (endotoxin)
Ex?
A is the active subunit and B is the binding subunit
B binds to a receptor that leads to internalization
A targets cellular function
Ex? cholera toxin
B-subunit binds to intestinal epithelial cells
A-subunit activates GPCR/Adenylyl Cyclase, leading to diarrhea
drug resistance in bacteria
examples and what they do?
plasmid encoded
they have degrading enzymes:
directly destroy the drug (B lactamases)
alter target:
change the structure or sequence of the Ab target
altered PBP’s
altering enzymes:
chemically modify the drug
efflux pump:
transport the drug out
