Lecture 4) example bacteria pathogens

Question 1

what is an endogenous infection?

Answer 1

an infection caused by an agent already in the body that was previously inapparent or dormant
eg stapylococcus aureus

Question 2

what is an exogenous infection?

Answer 2

an infection caused by an exogenous agent that has entered the body
eg C. diff

Question 3

what is the difference between a HAI and HCAI?

Answer 3

HAI = hospital acquired infection, only found in hospitals 
HCAI = healthcare acquired infections, can be found in hospitals, clinics, dentists etc

Question 4

what are some of the common HAIs?

Answer 4

GI infection
infections post surgery
IV cannulae 
skin infection
urinary catheter

Question 5

name some of the factors that impacts the spread and control of infections

Answer 5

social and environmental factors
health education
food safety
vector control - chemoprophylaxis - administration of antibiotics
outbreak investigation - infection control

Question 6

what does chemoprophylaxis mean?

Answer 6

the use of drugs to control disease/infection

Question 7

what are emerging infections?

Answer 7

infections that are rapidly in incidence/geographical range

Question 8

what are some of the characteristics of emerging infections?

Answer 8

money is being invested to protect against outbreaks
viral outbreaks more common than bacterial outbreaks - viral generally more serious and harder to treat
global warming means new pathogens in different places leading to infections and diseases that have never been seen before in that location

Question 9

how many phospholipid bilayers do gram negative bacteria have?

Answer 9

2

Question 10

do gram negative bacteria have a thin or thick peptidoglycan layer?

Answer 10

thin

Question 11

where do most gram negative bacteria fall into on the tree of life?

Answer 11

proteobacteria

Question 12

describe the outside phospholipid bilayer of gram negative bacteria

Answer 12

asymmetric

Question 13

why are gram negative bacteria called lipopolysaccharides?

Answer 13

they have carbohydrates on the outside of the polysaccharide layer

Question 14

what infection does Neisseria meningitidis cause?

Answer 14

meningitis

Question 15

how is Neisseria meningitidis classified?

Answer 15

by their serogroup

Question 16

how are Neisseria meningitidis classified using serogroups?

Answer 16

due to how a panel of antibodies recognise certain carbohydrate groups on the bacteria

Question 17

what is a serogroup?

Answer 17

a distinct variation within a species of bacteria use to classify them

Question 18

what subsequent infection can meningitis cause?

Answer 18

septicaemia

Question 19

is Neisseria meningitidis encapsulated? if so, describe it

Answer 19

encapsulated in a slime layer

Question 20

what is the function of the capsule on N. meningitidis?

Answer 20

if it was uncapsulated it would be taken up by phagocytes and destroyed
it is a mechanism that has evolved to avoid the host’s immune system

Question 21

what class is N. meningitidis?

Answer 21

beta proteobacteria (gram negative)

Question 22

10-15% of the population have N. meningitidis in their nasopharynx but dont show symptoms of meningitis, why is this?

Answer 22

the bug is asymptomatic

Question 23

N. meningitidis is said to have antigenic variation. what does this mean?

Answer 23

it can cross barriers and turn capsule on therefore avoiding phagocytes of the host’s immune system
can enter the meninges and cause infection

Question 24

why is there currently no MenB vaccine?

Answer 24

the MenB subgroup express the exact structure of the host’s carbohydrate
hard to create a vaccine that will target the foreign cell when they have the same structure as the hosts cell

Question 25

what concept has been introduce to solve the problem of having no MenB vaccine?

Answer 25

reverse vaccinology

Question 26

what is reverse vaccinology?

Answer 26

used to predict the epitope of the virus

Question 27

what is an epitope?

Answer 27

the part of the antigen that is recognised by the immune system

Question 28

how would reverse vaccinology be used to create a vaccine for MenB?

Answer 28

from examining genes on the surface of MenB, found 4 protective surface lipoproteins that are unlike the host's surface proteins vaccine could be created to target one/all of these proteins

Question 29

give an example of a gram positive bacteria?

Answer 29

diphtheria

Question 30

what is the route of infection for diphtheria?

Answer 30

airborne

Question 31

give a description of the morphology of diphtheria

Answer 31

asymmetric club-like all grouped at one end

Question 32

where in the body does diphtheria pathogenise?

Answer 32

nasopharynx

Question 33

is diphtheria an endogenous or exogenous infection?

Answer 33

exogenous | external pathogen that enters the host

Question 34

what makes diphtheria toxic?

Answer 34

diphtheria releases a toxin that kills host cells and spreads systematically to the heart and lungs

Question 35

what type of toxin does diphtheria release and what does it do?

Answer 35

``` AB toxin (main virulence factor of diphtheria) A = activity B = binding acts on EF2 ```

Question 36

the AB toxin in diphtheria acts on EF2. what is EF2 and what are the consequences of the toxin acting on this?

Answer 36

EF2 = elongation factor involved in translation when targeted by AB toxin = no proteins made = cell death = kills you

Question 37

name the vaccine against diphtheria

Answer 37

DTap vaccine

Question 38

what are the 4 levels of emerging infections?

Answer 38

1) exposure 2) infection 3) transmission 4) epidemic spread

Question 39

describe the introduction factor of emerging infections

Answer 39

have to determine where these infections are coming from | predict what/when the next bad outbreak will be and make a vaccine for it before it can cause an epidemic

Question 40

describe the establishment and dissemination factor of emerging vaccines

Answer 40

agents have to spread to be able to cause an epidemic harder for pathogens to achieve this as hopefully introduction factor will have been achieved and therefore an epidemic will have been avoided

Question 41

what technique is used to predict the next big epidemic?

Answer 41

genome sequencing

Question 42

what is a zoonotic disease?

Answer 42

a disease that normally exists in animals but can infect humans cases have now been reported of human infections spreading to animals

Question 43

give an example of a zoonotic pathogen and describe it

Answer 43

steptococcus suis gram positive present in swine industry

Question 44

what zoonotic infections can be caused from streptococcus suis?

Answer 44

meningitis septicaemia arthritis

Question 45

describe the process of genome sequencing in streptococcus suis

Answer 45

sequence different strains determine core genome and pan genome the more genes that are sequenced, the less genes that are similar therefore, core genome decreases in size and pan genome increases in size

Question 46

what can the genome sequencing of step. suis tell us?

Answer 46

the strain infecting humans had a type 4 secretion system proven by pulsed field gel electerophoresis T4SS thought to stimulate host immune reaction observed with streptococcal toxic shock like syndrome (STSLS)