What makes some bacteria virulent?

what negative effects on the human host can be caused by endotoxin? X3

-Endotoxin can cause fever, widespread inflammatory response, and damage blood vessels.

how can bacteria avoid phagocytosis (4 ways)

-Killing phagocytes with toxins -Changing the antigens that are present on their surface -Hide their antigens with a capsule or slime layer -Binding to phagocytes in a way that prevents closer contact, inhibiting phagocytosis

how can bacteria survive phagocytosis (x3) (how can microbes survive in macrophages)

-Preventing fusion of the phagosome with the lysosome -Surviving exposure to the enzymes from the lysosome(surviving in the phagolysosome) -Escaping the phagosome to live in the cytoplasm of the phagocyte

which two of those exotoxin groups trigger a more extreme immune response

4. pyrogenic toxins 5. superantigen

Superantigen: what does it do? how?

: Activates a large percentage of T-cells in the immune system, leading to a huge inflammatory response, opening up too many capillaries, leading to a drop in blood pressure and shock

cytotoxins : what effect do they have on the host

: inhibit protein synthesis or disrupt membranes, can harm heart, liver, or other organs (eg diptheria)

redefine exotoxins

A toxin released into the surrounding medium. Sometimes an enzyme

Virulence Factor

A trait of a pathogen that enhances the pathogen's disease-producing capability.

the specificity of what virulence factor could explain why bacteria are host specific?

Adherance (adhesion factors)

do our bodies have alot of iron to supply those invading bacteria?

Although there is a lot of iron in our bodies, it is mostly bound to various molecules, so there is very little free iron

where can bacteria hide?

Bacteria can hide in phagocytes or other cell types. In some cases they can be in a dormant state for many years.

role of the polysaccharide chain of an endotoxin

Polysaccharide chain has little toxicity on its own, but removal reduces virulence of the bacteira

list two examples of bacteria that produce superantigens

Produced by Staphylococcus, Streptococcus and others

two categories of toxins

endotoxins and exotoxins

enzymes v defensins deposited to the engulfed bacterial cell

enzymes work to degrade proteins, lipids, and cabrohydrates and defensins have antimicrobial peptide properties

list three cell appendages that act as adhesion factors involved in attachment of bacteria to host cells

fimbriae, pili, flagella

the extreme immune response triggered by pyrogenic toxins and superantigens leads to what

immunopathology

do toxins usually obviously help the pathogenic bacteria?

in many cases the effects of toxins are not of any obvious importance to the survival or propagation of the bacteria

___ is frequently a limiting nutrient for bacteria that have infected a human

iron

some pathogens are able to survive and replicate inside what specific white blood cell upon engulfment

macrophages

toxic shock syndrome is caused by which class of exotoxin

pyrogenic toxins

pyrogenic toxin: what effect (+how) do they have on the host

stimulate the release of cytokines, causing fever

immunopathology

study of diseases resulting in dysfunctions within the immune system where the hosts immune response causes the majority of the symptoms and possibly rlly significant damage

invasion factors

type of virulence factor that includes enzymes that help break down the extracellular matrix, cell membranes, or blood clots that would otherwise impede the spread of bacteria

when are adhesion factors especially useful

when they are colonizing in a place where they are in danger of being washed away (urinary tract or digestive tract for example)

usually does the endotoxin exist bound to the bacterial cell it is helping?

yeahj

how are endotoxins attached to that outer membrane?

. It has a lipid portion that anchors it to the membrane as well as a polysaccharide chain outside the cell.

most of the toxicity of an endotoxin comes from what structural component

. Most of the toxicity comes from the lipid portion.

steps of phagocytosis by white blood cells (1-4)

1. a phagocyte engulfs a bacterial cell 2. that confines the bacterial cell to a phagosome 3. lysosomes fuse with the phagosome, depositing enzymes and defensins 4. all of which kill the bacteria

Virulent bacteria have several mechanisms to avoid destruction by the immune system:

1. avoiding phagocytosis 2. surviving phagocytosis 3. becoming dormant and hiding

list the five main types of exotoxins

1. enterotoxin 2. neurotoxin 3. cytotoxin 4. pyrogenic toxins 5. superantigen

nutrient acquisition

Destruction of cells and extracellular matrix by invasion factors also makes nutrients available for the bacteria.

what could happen to the endotoxin if the bacterial cell dies?

Endotoxin generally remains associated with the bacterial cell but can be released if the cell dies or when it undergoes cell division.

endotoxins : where do we find them? on what sort of bacteria?

Endotoxin is found in the outer leaflet of the outer membrane of gram-negative bacteria

Exotoxins

Exotoxins are protein based, and released from bacterial cells, sometimes injected directly into a host cell. housed by both gram negative and gram positive

compare the effect of endotoxin bound to bacterial cell vs released from bacterial cell

It has some toxic effects when associated with the cell but exerts a much stronger effect when it is released.

macrophages

Macrophages are long-lived, and can play a role in long-term infections by becoming a "home" for pathogens.

how would adherance of a bacteria to a host be specific(x2) ? are some non specific?

May be very specific via protein-protein interactions OR May be specific to a particular cell type tho its important to note that Non-specific adhesion also exists

compare the normal T-cell response to an exotoxin vs a superantigen

Normal T-cell response activates .001% or less of the body's T-cells. Superantigen activates up to 20% of the T-cells, leading to a huge inflammatory response and shock.

how have bacteria adapted mechanisms to gather the bound iron?

Some bacteria secrete molecules called siderophores which chelates iron. The bacteria can then import the siderophore to gather the bound iron.

how do invasion factors directly act on host tissue?

They disrupt and penetrate host tissue so that the bacteria may invade, gaining access to new habitat.

How do virulence factors make a pathogen more virulent? (x4 ways)

They facilitate colonization, They help with nutrient acquisition They enable bacteria to avoid or resist the host immune system They are toxins

Toxins

Toxins are substances produced by bacteria that injure host cells and tissues

how normally would a bacteria be killed by phagocytosis?

When phagocytes engulf bacterial cell, the bacterium is confined to a membrane bound compartment called the phagosome. This fuses with a lysosome which contains various enzymes that digest the bacteria.

adhesion factors

a type of virulence factor that supply the bacterial cell with appendages and/or a capsule/slime layer that help the bacteria stick to host tissues

neurotoxin: what effect does it have on the host

affects nerve impulse transmission (eg tetanus and botulinum toxin)

how do virulence factors facilitate colonizations? (2 possible ways)

by adhesion to or invasion of tissue

how do some toxins clearly help pathogenic bacteria

by directly damaging immune cells or by killing other cells, releasing nutrients

enterotoxin: what effect does it have on the host

cause intestinal distress (eg food poisoning)