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University - Microbiology > Pathogenesis > Flashcards

Pathogenesis Flashcards

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1
Q

What is a pathogen

A

Any agent that can cause disease
Similar to parasites

One organism using resources of another in a way which is not beneficial to the host.

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2
Q

Differences between parasites and pathogens

A

Cant see virus with naked eye

Can see parasites

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3
Q

What are prions

A

Infectious proteins that make correctly folded proteins folded incorrectly

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4
Q

What makes a successful pathogen

A

Gains access to the host

Locate nutritionally compatible niches

Avoid, subvert, or circumvent the host innate and adaptive immune response

Access host and resources

Exit and spread to new host (transmission)

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5
Q

When does infection occur

A

Access host resources and replicate

Not all exposure to pathogens result in disease

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6
Q

What is the innate immune system

A

Non-specific

Rapid

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7
Q

What is the adaptive immune system

A

Highly specific

Slower

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8
Q

What is virulence

A

Measure of disease severity

Mortality - number of deaths

Morbidity - number of cases

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9
Q

How do you measure pathogen success

A

“is it still around”

Infectious dose - number of individual particles required for infection

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10
Q

What is the mortality rate of ebola, plague, rabies and vCJD

A

ebola - 90%

Others - 100%

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11
Q

What are virulence factors

A

Adhesins - Find a niche and colonise host

Capsules (S-layer) - immune evasion/survival in host

Digestive enzymes - Finding a niche, colonizing and finding host resource

Toxins - Reprogram host biology to benefit the pathogen - make you sick

Stealth mode - Absence of outer-surface structures (immune evasion)

NOT for causing disease

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12
Q

What number of lower respitory infections are deaths worldwide

A

3.2 million

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13
Q

How many diarrhoeal deaths

A

1.4 million

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14
Q

How many TB deaths

A

1.4 million deaths

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15
Q

How many HIV deaths

A

1.1 million

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16
Q

What percentage of deaths world wide are from pathogens

A

54%

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17
Q

Who proved germ theory

A

Robert Koch

Established a scientific basis linking microbes and diseases

Pioneered the use of pure cultures to understand infectious diseases

States many diseases are caused by microbes

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18
Q

What did Robert Koch demonstrate germ theory with

A

bacterium Bacillus anthracis (anthrax)

Invented petri dish (hi Adam and Meg and Aidan)

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19
Q

What are Koch’s postulates

A

To prove a specific pathogen causes a specific disease

Host + pathogen = disease

Healthy rabbit never contains anthrax

Unhealthy rabbit always has anthrax

Microbe is isolated from the diseased host and grown

Inject healthy rabbit with anthrax and it becomes unhealthy

Same strain is obtained from the new host

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20
Q

What are the main advances in combating disease in the last 200 years

A

Clean water and better diet

Improved sanitation

Less overcrowding in urban areas with better living conditions also
contribute.

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21
Q

What are vaccines

A

Chemical agents which prime the adaptive immune system to repel a pathogen

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22
Q

What is immunity through vaccination

A

After vaccination, if the subject can be exposed to the pathogen
and does NOT develop the disease, they are said to be immune.

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23
Q

What is IgG

A

Default antibody

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24
Q

What is IgM

A

5 IgG molecules

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25
Q

What does attenuated mean

A

Damaged particles

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26
Q

What is inactivated

A

Wont replicate

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27
Q

Who invented vaccination

A

Lady Montagu

Directly added pus from smallpox into open vein of patient

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28
Q

What did Edward Jenner discover

A

Cross protection - inoculated a person with cowpox and they were then protected from smallpox

Can vaccinate someone from a disease without using the disease

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29
Q

What is the last therapeutic option

A

Antibiotics

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30
Q

What are antibiotics

A

Chemicals produced by bacteria and fungi that inhibit or kill other microbes

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31
Q

Who invented penicillium

A

Alexander Fleming

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32
Q

Who did the first use of penicillin

A

Dr Cecil Paine

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33
Q

What did Florey and Chain discover

A

successfully manufactured the drug from the liquid broth in which penicillin grows.

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34
Q

How many lives has penicillin saved

A

between 80 and 200 million

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35
Q

What is the family of penicillins

A

Different types of penicillin for different usage

Injection only, orally, narrow spectrum, broad spectrum, extended spectrum and resistant to B-lactamase enzymes

36
Q

What does penicillin target

A

Cell wall synthesis

37
Q

What do antibiotics target

A

Cell wall synthesis

Protein synthesis

Cell membrane integrity

Nucleic acid function

Intermediary metabolism

38
Q

What is a symptom

A

A change in body function that is felt by a patient because of a disease
“I feel a bit tired”

39
Q

What is a sign

A

A change in the body that can be measured or observed because of disease
“temperature is high”

40
Q

What is a syndrome

A

A specific group of signs and symptoms that accompany a disease

High temperature, Feeling tired, Cough, Confusion

41
Q

What diseases can streptococcus pneumoniae cause

A

Pneumonia, sepsis, Meningitis

42
Q

How many ways can pneumonia be caused

A

Bacterial, Viral and Fungal

Symptoms and signs are identical

43
Q

What is the most abundant life form on the planet

A

Bacteria

44
Q

What does the microbiota do

A

Help with digestion

Metabolism

Immune function

Mood

45
Q

What is commensalism

A

One organism benefits and the other is unaffected

46
Q

What is mutalism

A

Both organisms benefit

47
Q

What is parasitism

A

One organism benefits at the expense of the other

48
Q

What is Clostridium Difficle

A

Pathogen - Clostridium difficile

Disease - CDI

Classification - Spore forming, Gram-positive bacteria

Symptoms - Diarrhoea, Colonisation and inflammation of the colon

Virulence - Mortality rate of 9%

49
Q

What is an opportunistic pathogen

A

Microbes which are not normally pathogenic but can cause infection or disease if the host is compromised

50
Q

What are hospital acquired infections

A

These infections are acquired because of a hospital stay

Usually, patients are the cause of their own illness not the hospital

51
Q

How does urbanization effect pathogenesis

A

More than 50% of the world live in urban areas

Higher population densities drive many potential routes of transmission

52
Q

What is Vibrio cholerae

A

Pathogen - Vibrio cholerae

Classification - Gram - negative

Disease - Cholera

Symptoms - Large amounts of watery diarrhoea (rice water stool)

Virulence - Death through severe dehydration - Can be 1% mortality if treated quick

Transmission - Faecal-Oral route

MVF - Cholera toxin

Treatment - Oral REHYDRATION`

53
Q

What was the first historical cause of epidemiology

A

Broad street water pumb for Vibrio cholerae

54
Q

What is epidemiology

A

Study of where and when diseases occur to control

spread of disease

55
Q

What are the principles of epidemiology

A

Identify first person to have the disease
‘Patient zero’
• Identify anyone who had contact with
that person
• Identify the reservoir for the pathogen
• Blocking or contain it

56
Q

What are the struggles of epidemiology

A

Difficult for new pathogens
• Disease must first be recognised
• Many already infected by then

57
Q

What is an epidemic disease

A

disease acquired by
many hosts in a given
area in a short time

58
Q

What is an endemic disease

A

Disease constantly present in a population

59
Q

What is a pandemic disease

A

Worldwide epidemic

60
Q

What is - Salmonella ‘typhi’

A

Pathogen - Salmonella enterica serovar Typhi

Class - Gram-negative bacterium

Disease - Typhoid Fever

Symptoms - Rash (Rose Spots) - Symptoms are non-specific and extremely variable

Reservoir - Human carriers (colonised gall bladder), 1-3% of people will permanently carry the disease

Transmission - Faecal-Oral route

Virulence - Mortality rate is about 30% without treatment.

61
Q

What is Polio Virus

A

Pathogen - Polio Virus

Class - + strand RNA virus

Disease - Polio

Symptoms - Irreversible paralysis (1/200), muscle weakness, atrophy, deformities, twisted feet or legs

Reservoir - Faecal - Oral route, usually via a contaminated water source

Treatment - Vaccine - Attenuated (weakened) virus

62
Q

Why is polio virus vaccine an imperfect solution

A

In very rare cases, the virus can revert into a form capable of causing disease and infecting others (OPV paradox)

In extremely rare cases some
immunocompromised individuals appear to
become ‘healthy carriers’ - Excreting large
amounts of active Polio virus for long periods of
time

Polio vaccine is extremely safe to the person receiving
the vaccine – but what about everyone else

63
Q

What are famous examples of healthy carrierr

A

Typhoid Mary - thyphoid

Birmingham man - Polio

64
Q

What is Yersinia Pestis

A

Pathogen - Yersinia pestis

Disease - Bubonic plague, Pneumonic plague

Symptoms - Buboes (swollen lymph nodes), Pneumonia

Virulence - extremely high mortality if untreated, bubonic - 50%, pneumonic - 90-100%. Treatable if less than 24hrs since symptoms

Reservoir - Rodents, Priarie dogs - Rodent fleas, Human respiratory aerosol (pneuomonic)

65
Q

What type of pathogen is Yersinia pestis

A

Zoonotic

66
Q

What is Epizootics

A

Animal equivalent of an epidemic

67
Q

What can pathogens infect

A

Any organism apart from viruses

68
Q

What is Phytophthora infestans

A

Pathogen - Phytophthora infestans

Disease - ‘Potato Blight’, Late blight

Virulence - Approaching 100% of crops

Treatment - Fungicides and copper sulphate

Blight makes soil full of spores so the field is no longer usable

69
Q

Where do potatoes originate

A

South America

70
Q

Why is blight not a problem in South America

A

Wide variety of genetically different potatoes. Europe has a genetic bottleneck

71
Q

What is influenza virus

A

Pathogen - Influenza virus

Disease - Influenza ‘flu’

Virulence - Very varied 0.01% - 50%‘newer’ strains have higher case fatality rates.

H1N1 (Hemagglutinin 1 and Neuraminidase 1)

Flu weakens the immune system so that secondary infections are common

72
Q

How are new influenza viruses made

A

Re-assortment of genetic material
generates ‘new’ influenza virus particles

Bird virus + human virus –> Swine cell –> new reassortant virus

73
Q

What is Zika Virus

A

Pathogen - Zika

Disease - Zika virus disease

Virulence - Extremely low, most people have no symptoms

Transmission - Mosquito (aedes)

74
Q

How are new diseases identified

A

A disease is first identified as a geographically clustered pattern of symptoms and signs

75
Q

What was the factor that identified zika

A

Microcephaly in babies (small skull –> small brain)

76
Q

What is the Aedes mosquito a vector for

A

Dengue virus

Zika virus

77
Q

What is epidemiological surveillance

A

Epidemiological surveillance is the collection, analysis
and dissemination of public health data

Takes time, can be inaccurate

Correlation based data falls
very short of ‘cause and effect’

78
Q

What is the updated Zika pathogen information

A

Sexually transmitted (men - 6 month and women - 8 weeks)

Associated with birth defects microcephaly, Guillain–Barré syndrome

79
Q

Where is Zika found

A

It is not limited to areas where the mosquito is found

80
Q

What did epidemiological surveillance discover in the Zika virus

A

Set up the Zika Birth Defects Surveillance,

Zika-associated birth defect rate in the US ≈ 5%
Chances of any pregnancy having a birth defect ≈ 3%

81
Q

What is Ebola

A

Pathogen - Ebola virus

Disease - Ebola virus disease, Ebola hemorrhagic fever

Symptoms - bleeding

Virulence - Highly virulent, 40-90% mortality

Reservoir - Unknown thought to be zoonotic

Treatment - Currently untreatable

Named after the ebola river in DRC

82
Q

What is the biggest challenge to modern medicine

A

Antimicrobial resistance

83
Q

Why is AMR such a big deal

A

The problem is the rate
of drug discovery has
sharply declined

The continued use of
antibiotics has driven
selection for resistant
strains

Without antibiotics
• Relatively minor infections would become life threatening
• Surgery
• Child birth
• Chemotherapy (for cancer treatment)
- ‘anyone who is immunocompromised’
• Infectious diseases would claim many more lives
- particularly the elderly and the very young

84
Q

Why is AMR so complex

A

Each antibiotic has a different target, each bacterial pathogen has a different virulence, characteristic and survival strategies and the resistance mechanisms are varied and poorly understood

85
Q

What are antibiotics

A

chemicals produced by bacteria and fungi that

inhibit or kill other microbes

86
Q

An infectious disease state is…

A

when a biological conflict occurs between host and pathogen

University - Microbiology (8 decks)

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