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Biology 6.1 > Bacteria and disease > Flashcards

Bacteria and disease Flashcards

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1
Q

What are pathogens

A

Microorganisms that cause disease

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2
Q

How can you investigate microorganisms even though they are small

A

By culturing them

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3
Q

What is culturing

A

Growing large numbers of the microorganisms so they can be measured in some way

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4
Q

What are the most cultured organisms

A

Bacteria and fungi

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5
Q

Why is important to take great care when culturing

A

There’s a risk a mutant strain can grow that may be pathogenic
there is a risk of contamination
When culturing a pure strain anything from the air will contaminate it

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6
Q

What are some health and safety precautions that must be followed when culturing

A

Making sure the equipment is sterile
Once the culture has grown it cannot leave the lab
Sterilize culture at 121 degrees got 15mins

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7
Q

What are the steps needed for culturing microorganism

A

1) Find microorganism you want to culture
2) Right nutrients to grow microorganisms (medium)
3) Introduce microorganism to medium
4) The sterile broth in the flask
5) Flsk is then stoppered again with cotton wool
6) Flask is incubated

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8
Q

What is the nutrient medium

What form does it come in

A

Usually nutrient agar

Can come in nutrient broth (nutrients in liquid) or solid form

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9
Q

What is agar

Why is agar useful

A

A jelly extracted from seaweed

It doesn’t melt until it is heated to 90 degrees

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10
Q

How are most microorganisms grown

A

Medium enriched in good protein such as blood yeast or meat

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11
Q

What is a selective medium

A

A medium in or on which only a select group of microorganisms with particular requirements will grow

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12
Q

What is a selective medium important for

A

Identifying the particular mutant strain of microorganisms and antibiotic resistance
Identifying microorganisms that have been genetically modified

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13
Q

What is inoculation

A

Getting bacteria onto your agar or into your broth

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14
Q

How do you get a pure culture

A

isolation is needed

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15
Q

How does isolation take place

A

1) Growing a culture under anaerobic conditions
2) Indicator media that cause certain types of bacteria to change color
3) Different nutrients to grow different microorganisms

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16
Q

How can bacteria or single-celled fungi cultured in a nutrient broth be counted

A

Using a microscope and haemocytometer

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17
Q

What is a haemocytometer

A

Consists of a specialised thick microscope slide with a rectangular chamber that holds a standard volume of liquid

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18
Q

Why is the sample of nutrient broth diluted with trypsin blue

A

The dye stains dead cells blue so you can identify them and count the living organisms

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19
Q

What does the corner of the haemocytometer have

A

Squares divided into 16 smaller squares

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20
Q

Why is the haemocytometer calibrated

A

So the number of bacterial and fungal cells in one set of 16 squares equates to the number of cells X10 to the ower of 4 of broth

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21
Q

What is turbidimetry

What happens

A

An alternative way of measuring the number of cells in culture (a specialized form of colorimetry)
As the number of bacterial cells in a culture increase, it becomes increasingly cloudy)

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22
Q

What does a colorimeter measure

A

How much light passes through a sample

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23
Q

How is a calibration curve produced

What does it help us measure

A

By growing a control culture and taking samples at regular time intervals
The number microorganisms using turbidimetry

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24
Q

What is diluting plating

What is used to find

A

Another way of counting microorganisms in a culture

used to find total viable cell count

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25
Q

What is the technique dilution plating based on

A

The idea that each colony on an agar plate have grown from a single, viable microorganism on the plate

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26
Q

What happens if the number of colonies is multiplied by a dilution factor

A

Then the total viable count for the original sample can be determined

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27
Q

How can the accuracy of dilution plating after finding the mean measured

A

by using a haemocytometer to count the original culture

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28
Q

What is a simple way to assess the growth of a cultured fungi

A

To measure the diameter of the patches of mycelium

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29
Q

Explain the process if finding the growth of cultured fungi

A

1) Different petri dish at different temperature
2) measure the diameter of each fungal colony
3) The temperature that has resulted in the largest mean for growth is the optimum temperature

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30
Q

What is the generation time

A

The time between bacterial division

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31
Q

Do bacteria rapidly divide

A

Yes they always divide very quickly

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32
Q

Why do we use log to deal with bacteria

A

Because bacteria divide rapidly and log makes it easier to deal

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33
Q

How is log represented on the graph

A

Y-axis is in powers of 10 and x-axis is time/hrs

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34
Q

What is the exponential growth rate formula

What does each stand for

A 
K=log10Nt -log10N0
   ----------------------------              
   log102 x t
k=exponenyial growth rate 
Nt=no.of organs at time t 
No=No.of organisms at time 0
k = exponential growth rate constant 
t= the time the colony has been growing
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35
Q

What are the 4 stages for this growth curve

A
  1. lag phase (When bacteria are adapted to their maximum environment and are not yet reproducing at their maximum rate)
  2. log phase (When the rate of bacterial production is close to or at theoretical maximum)
  3. stationary phase (As the no. of new cells formed by binary fission is equal t the no. of cells dying)
  4. death phase (when reproduction has almost ceased)
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36
Q

Give two reasons why the exponential growth of bacteria doesn’t continue

A

1) Reduction of nutrients available

2) Build up of waste products

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37
Q

Give an example of some diseases caused by bacteria

A

Tonsillitis, tuberculosis, and pneumonia

38
Q

What does understanding bacteria acts us agents of infections help us avoid

A

Infections and treat bacterial diseases effectively

39
Q

What happens once pathogenetic bacteria gets into the body

A

They cause the signs and symptoms of disease in a number of ways

40
Q

How do most bacteria make people sick

A

Through the toxins, they make as a by-product of their metabolism

41
Q

What are toxic classified as

A

Endotoxins and Exotoxins

42
Q

What are endotoxins

A

Endotoxins are lipopolysaccharides that are an integral part of the outer layer of the cell wall of Gram-negative bacteria

43
Q

What acts as the toxin in Endotoxins

A

The lipid part of the lipopolysaccharides

44
Q

What effect do endotoxins have

Whats the pathogenic effect

A

Have an effect around the site of infection by the bacteria.

The pathogenic effects produced are things such as diarrhoea, fever, and vomiting

45
Q

What can antibiotics lead to

A

Further endotoxin release, due to the lipopolysaccharides component of the cell wall

46
Q

How does the salmonella bacteria act

A

The bacteria invade the lining of the intestine and the endotoxins cause inflammation
The cell no longer absorbs water so the faeces become liquid
The gut then goes into spasms of peristalsis that results in diarrhoea

47
Q

How is salmonella spp. spread

A

By ingestion of food and water contaminated with infected faeces

48
Q

Where does the salmonella bacteria live

A

Live in the gut of many food animals and easily contaminates the meat

49
Q

Why is salmonella rare in the UK

A

The chicken is vaccinated of the disease

50
Q

Why are antibiotics useless for this disease

A

Even though it allows them to feel better it acts as a carrier for longer

51
Q

How can salmonella be avoided

A

Cooking the meat thoroughly
Washing hands after handling raw meat
Washing hands after using the toilet

52
Q

What are you Exotoxins

A

Are usually soluble proteins that are produced and released into the body by bacteria as they metabolise and reproduce in the cells of their hosts

53
Q

How are exotoxins produced

A

Gram-positive and Gram-negative bacteria

54
Q

Give examples of that some exotoxins do

A

Some damage cell-membrane causing cell breakdown
internal bleeding
competitive inhibitors to neurotransmitters
Directly poison cells

55
Q

When do Staphylococcus spp. cause disease

A

If they get inside the tissues of the body, if the skin flora is changed or if the person has a compromised immune system or has been receiving treatment such as chemotherapy

56
Q

What kinda bacteria is Staphylococcus spp.

A

Gram-bacteria positive

57
Q

What does s.aureus cause

A

Skin infections

Infections of the joints in septic arthritis

58
Q

What do both s.aureus and s.epidermis cause

A

Bacterial meningitis

59
Q

What are third-way bacteria acts as a pathogen

A

invading host tissues and damaging the cells

60
Q

What are the bacteria that causes tuberculosis

A

Bacterium mycobacterium tuberculosis

61
Q

How is Mycobacterium tuberculosis spread

A

By droplet infections

62
Q

Whose more vulnerable to tuberculosis (TB)

A

People who are malnourished, ill or have problems with their immune system

63
Q

How are people infected by Mycobacterium bovis

A

by drinking infected milk or living and working in close contact with cattle

64
Q

What does TB affect

A

The respiratory system, damaging and destroying lung tissues
suppresses the immune system making it less able to fight diseases

65
Q

What are the well-known symptoms of coughing

A

Coughing up blood and weakness

66
Q

What happens once the bacteria for tb is inhaled

A

It sits in the lungs and multiples

67
Q

What is a tubercle

A

Localised inflammatory response forming a mass of tissue when the immune system is healthy

68
Q

When does primary tb often take place

A

During childhood

69
Q

What adaptation does Mycobacterium tuberculosis have

A

Enables it to avoid the immune system, allowing some bacteria to survive the primary infection stage

70
Q

What are antibiotics

A

Medicines that either destroy microorganisms or prevent them from reproducing

71
Q

What is the principle of selective toxicity

A

A principle in which all modern antimicrobial drugs work against microorganisms

72
Q

What was the first successful antibiotic

Is it still used

A

Penicillin

Yes used globally

73
Q

Why are antibiotics effective

A

They disrupt the biochemistry of the bacterial cells

74
Q

What does bacteriostatic mean

A

The antibiotics used completely inhibits the growth of the microorganism

75
Q

What is tetracycline

A

Used to cure acne

76
Q

Give examples of a bacteriostatic antibiotic

A

respiratory tract infections and chlamydia

77
Q

What does bactericidal

A

It means it’ll destroy almost all the pathogens present

78
Q

when are bactericidal used

A

To treat severe and dangerous diseases

Also used to treat infections where the immune system is suppressed

79
Q

Give an example of bactericidal antibiotics

What does it treat

A

Penicillin

Used to treat skin infections, chest infections, and urinary tract infections

80
Q

Which one out of bactericidal and bacteriostatic kills all bacteria
What’s the difference in percentage

A

Bacteriostatic
100% bacteriostatic
99% bactericidal

81
Q

What factors does the effectiveness of antimicrobials depend on

A

1) Conc of the drug
2) PH
3) The susceptibility of the pathogen
4) Whether either the pathogen o the host tissue destroys the antibiotic

82
Q

When is an antibiotic only effective

A

If the microorganisms have a binding site for the drug and metabolic process or biochemical pathway with which the antibiotic interferes

83
Q

How does antibiotic resistance bacteria come about

A

By mutation to the antibiotic

84
Q

What is MRSA

A

An example of a superbug

85
Q

How can we reduce the number of antibiotic resistance

A

By using antibiotics sparely only when needed

86
Q

Where are superbugs commonly found

A

Hospitals and care homes

87
Q

What happens to patients that develop superbugs

A

They need to stay in hospital much longer

88
Q

How are Staphylococcus infections cured

A

Treated very effectively with methicillin

89
Q

What is Clostridium difficile

A

An anaerobic bacterium that is found in small numbers in the large intestine

90
Q

When does Clostridium difficile cause problems

A

When an antibiotic that damages the gut flora

91
Q

What are the rules that doctors have made to stop widespread of healthcare-associated diseases

A

1) Control the use of antibiotics
2) Hygiene measures
3) Isolation of patients
4) Prevention of infection coming into the hospital
5) Monitoring levels of healthcare-associated infections

92
Q

What has happened ever since rules were put up about healthcare-associated diseases

A

There has been a decrease in the disease spread

Biology 6.1 (1 decks)

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