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microbiology > lecture 3) concept of virulence and infectivity > Flashcards

lecture 3) concept of virulence and infectivity Flashcards

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Biology 101 flashcards
1
Q

define what is meant by the term disease

A

growth of pathogens that impairs tissue function

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2
Q

give an example of a disease in plants

A

rice blast fungus

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3
Q

what does the rice blast fungus do and what is it’s impact?

A

it is a plant disease that kills one of the most important food sources in the world
more rice means more people can eat which has an impact on the price of rice

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4
Q

name 3 different types of disease

A

genetic (aka metabolic)
disease of ageing
infectious disease

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5
Q

describe and given an example of a genetic disease

A

eg. cystic fibrosis

those with CF have a specific genotype due to impaired transport of Cl- across the cell membrane

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6
Q

describe and give an example of disease of ageing

A

eg. atherosclerosis
build up of plaque/cholesterol over a period of time
the older you are the more plaque will have built up in your arteries therefore based on age

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7
Q

describe and give an example of an infectious disease

A

eg measles

individual contracts outside agent

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8
Q

describe the MMR vaccine debate

A

we are close to eradicating the disease in the UK
people feared taking the vaccine would do you more harm than good
people stopped taking the vaccine
lead to measles outbreaks

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9
Q

define the term infection

A

a pathogen invades the host and begins growing in the host

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10
Q

what is a latent infection?

A

when a pathogen invades a host but doesnt cause disease

a disease is only caused when there is tissue impairment

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11
Q

give examples of latent infections

A

herpes, HIV, TB

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12
Q

name 3 possible ways infections can spread

A 
skin to skin contact (mites)
body fluids (HIV)
water droplets (legionella)
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13
Q

why is legionella so dangerous?

A

can be fatal as it is latent in the environment but can cause disease once inside the host

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14
Q

define the term pathogen

A

an organism that is capable of causing disease in a susceptible host

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15
Q

what is characteristic of the pathogens in normal microbiota?

A

they dont cause disease

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16
Q

what is a true pathogen?

A

an infectious agent that causes disease in virtually any susceptible host

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17
Q

what is an opportunistic pathogen?

A

potentially infectious agents that cause disease in individuals with healthy immune systems
eg candida; may cause disease in those who are immunocompromised, when in the presence of MRSE - v toxic

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18
Q

define the term pathogenicity

A

the capacity of the microbe to cause disease

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19
Q

what are some of the characteristics of pathogenicity?

A

microbial variable
discontinuous variable - either is or isnt pathogenic
only expressed in susceptible host therefore dependent on host variables

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20
Q

list 4 host variables

A

age
diet
stress
status of immune system

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21
Q

define the term virulence

A

amount of damage or disease that can be caused to the host

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22
Q

how would you measure virulence?

A

the unit is cells kills/those that caused disease

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23
Q

what does ID50 stand for?

A

the median infective dose

the amount of microorganism that will produce demonstratable infection in 50% of it test subjects

24
Q

what does LD50 stand for?

A

quantity of agent needed to kill 50% of test subjects

25
Q

are ID50s and LD50s the same for every microorganism?

A

no, ID50s and LD50s vary for each microorganism as some are more virulent than others eg TB vs C. diff

26
Q

name 3 influences of virulence

A

immunological status
physiological status
route of infection

27
Q

name 3 routes of infection

A

ingestion
skin
inhalation

28
Q

name 3 host influences on virulence

A

age
genetics
stress

29
Q

using an example, explain how the route of infection can determine the virulence of a pathogen

A

anthrax
cutaneous; found on the skin, causes sores, can be treated
inhaled; same number of spores inhaled as on the skin can kill you. inhaled anthrax has a lower ID50

30
Q

what is the impact of climate change on disease?

A

new climate = new diseases = new plant diseases = migration

31
Q

what is a virulence factor?

A

describes a microbial characteristic
caused by specific genes
intrinsic factor
outcomes dependent on host

32
Q

what is the first of koch’s molecular postulates?

A

the gene under investigation should be found in all pathogenic strains of a species but absent from non-pathogenic strains

33
Q

what is the 2nd of koch’s molecular postulates?

A

the gene causing the virulence but be expressed during infection

34
Q

what is the 3rd kochs molecular postulates?

A

inactivation of the gene causing virulence must lead to measurable loss of virulence
this loss must be less in microorganisms with unaltered gene

35
Q

what is the 4th kochs molecular postulate?

A

reversion or allelic replacement of mutated gene should restore pathogenicity

36
Q

how would you monitor gene expression using RNA sequencing?

A

sequence of the gene known
primer made to stick to product using 16S rRNA method
measure light emitted from the number of copies from a gene

37
Q

what is the copy number in PCR?

A

how many pieces of RNA is expressed at a certain time

38
Q

what is a limitation of the virulence factor concept?

A

hard to apply to microbes whose pathogenicity is limited (immunocompromised)

39
Q

what is meant by the term planktonic when describing bacterial state?

A

bacteria are in the aqueous phase

not stuck on a surface

40
Q

what is meant by the term biofilm?

A

bacteria are attached to a surface

41
Q

what is characteristic about the genetics between biofilms and planktonic bacteria?

A

they have different gene expression as they know if they are on a surface or not

42
Q

what is more susceptible to antibiotics; planktonic or biofilm bacteria? why?

A

planktonic more susceptible to antibiotics as a lower concentration of ABs needed
harder for AB to enter into middle of biofilm to target the bacteria
eg metal hip replacement: biofilm forms around the metal hip causing infection, no blood flow around the metal hip to take anti-microbial therefore need to repeat the surgery

43
Q

what is the impact of biofilms on the oil industry?

A

microbes attach to the steel and form biofilms
biofilms corrode the pipes
pipes then need to be replaced - expensive

44
Q

why would a microbe not have the same impact when grown in the presence of another microbe vs being grown individually?

A

more profound when together

45
Q

why would you need to find out what microbe it is that is causing infection when in the presence of other microbes?

A

need to find out what microbe it is causing the infection in order to treat it
different microbes require different treatment plans

46
Q

how would you find out what microbe is causing the infection when in the presence of another microbe?

A

look at its virulence factors

47
Q

what is cell-cell signalling?

A

different ways cells communicate using different chemicals they produce

48
Q

where does the name quorum sensing come from?

A

need a certain number of organisms to be present before chemicals are produced

49
Q

what is quorum sensing?

A

a type of cell-cell communication
chemicals thrown into environment (signal)
microbes sense the signal and move towards it (food sources, upregulate virulence factors)

50
Q

what is quorum sensing an example of?

A

cooperation

51
Q

what is the principle behind social organisation of bacteria?

A

some bacteria produce products needed by all bacteria
other bacteria dont produce these essential produce but use what the other bacteria have produced (cheaters, sense of hierarchy)
happens especially in biofilms

52
Q

what is the evidence for electrical signalling between bacteria?

A

some form networks and can move electricity from one place to another
could we harvest this electricity?
is it an example of neural activity?

53
Q

what is meant by the term epidemiology?

A

the effects of pathogens on populations

a measure of when and where they occur

54
Q

define the term incidence

A

the number of new cases of a disease in a given area/population

55
Q

define the term prevelance

A

the total number of new and existing cases

56
Q

how are incidence and prevelance expressed

A

as a ratio

I:P

microbiology (17 decks)

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