Pathogenicity mechanisms

Question 1

Bacteria can get into sterile body sites using :

Answer 1

Adhesins

Question 2

Virulence genes in bacteria are often the result of :

Answer 2

Lysogenic conversion

Housekeeping genes are usually rich in AT

Question 3

Virulence genes usually have higher contents of what nucleotides ?

Answer 3

CGs

Question 4

Usually upregulated by î temperature or population density ?

Answer 4

Virulence genes

Question 5

Asplenic patients are especially at risk of dying from infections with encapsulated bacteria. Why ?

Answer 5

No marginal B cells to make a IgM response i.e. Not even a T-independent response can occur. Since capsules are made out of polysaccharides, they evade phagoctyosis and T-dependent response.

Question 6

This specific type of bacteria is a pro at natural transformation :

Answer 6

Encapsulated bacteria.

This is why they can plug and play so many different capsule types.

E.g. Streptococcus pneumoniae, haemophilus influenzae, neisseria species such as N.meningiditis & N.gonorrheae.

Question 7

In what context is their upregulation of gene expression for biofilms ?

Answer 7

At high population densities

Biofilms are expressed as a result of quorum-sensing
(Auto-inducer system).

Question 8

Bacteria with multiple capsules types can switch them up as a way to evade the immune system. What is this called ?

Answer 8

Serotype switching.

Question 9

Undulant symptoms usually indicate an infection with an organism that is able to do what ?

Answer 9

Serotype switching.

Question 10

When microbes have antigens similar to human proteins, they can use immune mimicry to evade our immune system in the short term. In the long term, what is the consequence of this immune mimicry for us ?

Answer 10

Risk of type II or III HSRs

Question 11

Why do bacteria use hemolysins ?

Answer 11

A function of hemolysins is that the bacteria can utilize hemolysis to release and utilize nutrients from the host animal cells.

E.g. Iron

Hemplysins secreted by the bacteria have barrel shaped structures that can form portes in the membrane.

Question 12

What is the main cause for symptomatology in relation to bacterial infection ?

Answer 12

Inflammation.

More TLR binding, more NF-kappa-B, more production of IL-1 & TNF.

Question 13

What is the most pro-inflammatory PAMP ?

Answer 13

Lipid A.

It activated 2 separate kinase cascades and is held very securely because of CD14 coreceptors.

Question 14

What inflammatory cytokines are involved in fever ?

Answer 14

Il-6
Il-1
TNF-a

Question 15

In response to IL-1, acute phase proteins increase in plasma. What are 2 examples of acute phase proteins ?

Answer 15

CRP
MBL

Question 16

True or false.
Only PAMPs can cause î IL-1 & TNF-a and lead to septic shock ?

Answer 16

False

Question 17

Superantigens are molecules that permanently bind what, resulting in continuing production of IL-1 & TNF ?

Answer 17

MHC II & TCR

Question 18

Almost all A/B toxin genes are the result of lysogenic conversion. What is lysogenic conversion ?

Answer 18

This means of transferring genetic information, called lysogenic conversion, imparts genes with special functions to bacterial cells without such functions. For example, the bacterium Corynebacterium diphtheriae is the causative agent of diphtheria, but only when it contains the prophage of bacteriophage β, which codes for the toxin that is responsible for the disease.

Question 19

Binds to E2F in eukarotyic ribosomes present in respiratory epithelia, stoping translation.

Answer 19

Diphteria toxin

B unit binds respiratory epithelia
A unit ribosylates EF-2

Question 20

4B-subunit binds ciliated intestinal epithelia
A-subunit î cAMP

Answer 20

Cholera toxin

4-8 L per day of water stools.

Question 21

B-subunit binds to motor neurons
A subunit stops Ach release

Answer 21

Botulism toxin

Result in flaccid paralysis.

Question 22

What are the characteristics of endotoxins ?

Answer 22

Bacteria has to die to release the toxin;
Release of the toxin causes tons of inflammation.

Endotoxin = PAMP of some sort.

Question 23

What are the characteristics of exotoxins ?

Answer 23

Bacteria secretes toxin while its actively growing;
Toxin can have all sorts of effects because they are all different.

Superantigens, A/B toxins & pore-forming lysins.

Question 24

Staphylococcus aureus are very good at making X as a mechanism of resistance :

Answer 24

B lactamases.

Question 25

B lactam that crosses the placenta & safe to use during pregnancy ?

Answer 25

Ampicillin

Question 26

example of 2 atb that are contraindicated in pregnancy ?

Answer 26

Sulfamethoxazole/trimetoprim
Tetracylines