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KMMS > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What percentage of the world’s deaths are caused by infections?

A

33%

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2
Q

What are the two major emerging threats related to infection in high-income countries?

A
  1. Healthcare-associated infections

2. Antibiotic resistance

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3
Q

List the four major types of micro-organisms which cause human infectious disease

A
  1. Viruses
  2. Bacteria
  3. Fungi
  4. Protists
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4
Q

In 1876, who established that microbes can cause disease?

A

Robert Koch

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5
Q

Koch’s postulates: #1

A specific ___________ is always associated with a given disease.

A

microorganism

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6
Q

Koch’s postulates: #2

The microorganism can be __________ from the diseased animal and __________ in pure culture in the laboratory.

A

isolated, grown

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7
Q

Koch’s postulates: #3

The cultured microbe will cause __________ when transferred to a healthy animal.

A

disease

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8
Q

Koch’s postulates: #4

The _______ type of microorganism can be isolated from the newly _________ animal

A

same, infected

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9
Q

Do prokaryotic cells have a nucleus?

A

No

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10
Q

Do prokaryotic cells have internal membranes?

A

No

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11
Q

How is prokaryotic DNA organised?

A

One circular chromosome in a nucleoid

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12
Q

Which type of cells contain extensive and specialised organelles- prokaryotic or eukaryotic?

A

Eukaryotic

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13
Q

How are bacteria named?

A

Genus, then species

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14
Q

In the strain of E.coli known as “0157:H7,” what do the “O” and “H” refer to?

A

Different antigens

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15
Q

Bacteria are most helpfully classified by shape and _________

A

staining

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16
Q

The ability to take up stain is based on the __________ and accessibility of cell wall ____________________.

A

thickness, peptidoglycans

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17
Q

List the four layers encapsulating gram negative prokaryotic cells (from outermost to innermost layer)

A
  1. Capsule
  2. Outer membrane
  3. Peptidoglycan layer
  4. Plasma membrane
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18
Q

Which two layers make up the bacterial cell wall?

A

The outer membrane and the layer of peoptidoglycan

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19
Q

Gram-positive bacteria have a uniformly dense cell wall consisting primarily of

A

peptidoglycan

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20
Q

Which types of bacteria have a very this peptidoglycan layer and an outer membrane?

A

Gram negative bacteria

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21
Q

An __________ is a toxic, heath stable lipopolysaccharide substance present in the outer membrane of gram negative bacteria that is released from the cell upon lysis.

A

Endotoxin

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22
Q

What type of bacteria have lipopolysaccharide?

A

Gram negative bacteria

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23
Q

Gram negative bacteria have what toxic substance in their outer membrane layer?

A

Lipopolysaccharide

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24
Q

Peptidoglycans have 3-5 amino acid proteins, which is significant because it makes them resistant to

A

enzymatic destruction

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25
Q

What kind of enzymes assist with cross-linking of peptidoglycans?

A

Transpeptidase enzymes

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26
Q

Which class of antibiotic prevents the cross-linking of peptides by binding bacterial transpeptidases?

A

Beta lactam antiobiotics (penicillin,s cephalosporins, carbapenems)

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27
Q

Which class of antibiotic is only effective in gram positive bacteria?

A

Glycopeptides (e.g. Vancomycin)

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28
Q

Bacterial capsules are made up of

A

polysaccharides

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29
Q

What is the medical importance of the bacterial capsule?

A

It “hides” the immunogenic cell wall

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30
Q

Immunity requires antibodies to the _______

A

capsule

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31
Q

Which part of the bacteria confers virulence?

A

The capsule

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32
Q

Mobile genetic elements code for ________ and antibiotic resistent _______.

A

toxins, genes

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33
Q

These are DNA sequences that are able to move location in the genome

A

Transposons

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34
Q

Circular “extrachromosmal” DNA that replicates independently.

A

Plasmids

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35
Q

This type of independently replicating DNA can be passed down to progeny or transmitted between bacteria

A

Plasmids

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36
Q

Non-replicating, dormant form of bacteria that are resistant to drying, temperature, disinfection, and digestion.

A

spores

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37
Q

Bacillus spp and Clostridium spp are two examples of bacteria that can form ________

A

spores

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38
Q

Name four examples of bacteria virulence factors:

1. ___________ molecules

A

adhesion

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39
Q

Name four examples of bacteria virulence factors:

2. ___________ to degrade host proteins

A

Enzymes

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40
Q

Name four examples of bacteria virulence factors:

3. Degrade ___________ mediators

A

immune

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41
Q

Name four examples of bacteria virulence factors:

4. _________ host cells

A

Lyse

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42
Q

Gene regulation - bacterial growth. Describe what happens in the lag phase of bacterial growth

A
  • no increase in cell numbers
  • Adjustment to new environment
  • Gene regulation
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43
Q

Gene regulation - bacterial growth. Describe what happens in the log or exponential phase of bacterial growth

A
  • Cell doubling
  • Slope of curve = growth rate of that organism in that environment
  • This is where the person would have either a superficial infection, or bacteraemia
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44
Q

Gene regulation - bacterial growth. Describe what happens in the stationary phase of bacterial growth

A
  • Nutrients become depleted
  • Metabolites build up
  • Divison stops
  • Gene regulation
  • ABSCESS
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45
Q

Gene regulation - bacterial growth. Describe what happens in the death phase of bacterial growth

A
  • Exhaustion of resources

- Toxicity of environment

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46
Q

Bacteria are most helpful classified by ________ and staining

A

shape

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47
Q

Shape of Streptococcus and Enterococcus bacteria?

A

Coccus/cocci = round

48
Q

Shape of Enterobacter spp?

A

Bacillus/bacilli = rod-shaped; long

49
Q

Shape of Vibrio cholera?

A

Vibrio = comma-shaped

50
Q

Shape of Coccobacillus?

A

In between Coccus and Bacillus- oval

51
Q

Shape of Campylobacter jejuni (spirilium)?

A

Rigid spiral

52
Q

Shape of spirochete?

A

Coiled spirals

53
Q

What are the three requirements for successful viral infection?

A
  1. Enough virus
  2. Cells accessible, susceptible, and permissive
  3. Local antiviral defense absent or overcome
54
Q

List the 5 types of viral transmission:

A
  1. Horizontal (between members of the same species)
  2. Iatrogenic (Due to activity of a health care worker)
  3. Nosocomial (Infection occurs in hospital)
  4. Vertical (Transfer of infection between parent and offspring)
  5. Germ line (Agent transmitted as part of the genome - e.g. pro-viral DNA)
55
Q

What is the most common route of entry for viral infections?

A

Respiratory tract

56
Q

List the 5 methods of acquiring viral infections (body system “breach”)

A
  1. Respiratory tract
  2. Alimentary tract (eating, drinking, etc)
  3. Urogenital tract
  4. Eye
  5. Skin
57
Q

Viral infections can be ________, __________ or _________.

A

acute, chronic, latent

58
Q

This type of viral infection is characterised by a rapid onset of dz, a relatively brief period of symptoms, and resolution within days

A

acute

59
Q

These types of viral infections are caused by pathogens with slow growth rates, promoting an infection that is persistent for long periods.

A

Chronic

60
Q

This is an infection that is hidden, inactive, or dormant

A

Latent

61
Q

Can latent infections be transmitted to another host, even without any visible signs of disease?

A

Yes

62
Q

This is the capacity of a virus to cause disease in an infected host

A

Virulence

63
Q

This is the amount of virus needed to kill 50% of infected animals

A

LD 50

64
Q

How can virulence be quantified? (5)

A
  1. LD 50
  2. Mean time to death
  3. Mean time to appearance of sx
  4. Measurement of fever, weight loss
  5. Measurement of pathological lesions
65
Q

Viral genes affecting virulence fall into four classes:

1. Those that affect the abilty of the virus to ______

A

replicate

66
Q

Viral genes affecting virulence fall into four classes:

2. Those that modify the ______ _________ mechanisms

A

host’s defense

67
Q

Viral genes affecting virulence fall into four classes:

3. Those that enable the virus to ______ in the host

A

spread

68
Q

Viral genes affecting virulence fall into four classes:

4. Those which have intrinsic _______ _________ effects

A

cell killing

69
Q

This describes that capability of a virus to infect a distinct group of cells in the host

A

Tropism

70
Q

Tropism is determined by

A

the availability of virus receptors on the surface of a host cell.

71
Q

A _________ host is a person who can become infected by an infectious agent.

A

susceptible

72
Q

Name 5 risk factors that can accelerate risk of infection

A
  1. Age (< 6 months old, and in the elderly)
  2. Nutrition and sociocultural condition
  3. Open wounds/invasive procedures
  4. Suppressed immune system
  5. Presence and/or number of infectious organisms
73
Q

A ________ cell or host is one that allows a virus to circumvent its defenses and replicate.

A

permissive

74
Q

What is the most common type of test used to detect levels of antibodies?

A

Enzyme-linked immunosorbent assay (ELISA)

75
Q

ELISA assays are usually _________, using a reaction that converts the substrate into a coloured product which can be measured using a plate reader.

A

chromogenic

76
Q

Which type of serologic testing enables you to run multiple tests for different viruses simultaneously?

A

Automation and Random Access Analyser

77
Q

Which testing method is the best of non-cultivable viruses?

A

Viral nucleic acid detection testing (PCR)

78
Q

What is the most common type of viral nucleic acid detection test?

A

PCR

79
Q

What type of serologic test for viral infections can also quantify viral load?

A

PCR

80
Q

Explain concepts of viral prevention

A
  1. PPE: Gloves, masks

2. Vaccines, chemoprophylaxis, immunoprophylaxis

81
Q

Which four common viruses are there currently no vaccines for?

A
  1. HIV
  2. HCV
  3. CMV
  4. EBV
82
Q

HAART drugs are used to treat

A

HIV

83
Q

Lamivudine is used to treat

A

HBV

84
Q

Ribavarin and PEG intereron are used to treat

A

HCV

85
Q

Tamiflu is used to treat

A

Influenza

86
Q

Acyclovir is used to treat

A

HSV

87
Q

Ganciclovir is used to treat

A

CMV

88
Q

What are the 5 main methods used to diagnose infectious disease?

A
  1. Microscopy
  2. Bacterial culture
  3. Tissue culture
  4. Serology
  5. Molecular techniques (PCR)
89
Q

What type of laboratory test is more sensitive for detecting very small numbers of bacteria- microscopy or culture?

A

Culture

90
Q

What is the main strength of bacterial culture?

It’s good for bacteria you can _________ and ________.

A

stain, grow

91
Q

What type of lab test is best for antiobiotic susceptibility testing?

A

Bacterial culture

92
Q

Bacterial culture provides provisional identification of bacteria based on the bacteria’s ___________.

A

metabolism

93
Q

What is the time frame to achieve results in a bacterial culture?

A

24 hours for provisional identification,

48 hours to get definitive information

94
Q

What are the limitations of bacterial culture?

A
  1. Slow (definitive results take 48 hours)
  2. Labour intensive
  3. Some microorganisms are “unculturable,” such as syphilis
95
Q

How is HIV mainly diagnosed?

A

Serology

96
Q

This lab test can show the response of the immune system to pathogens

A

serology

97
Q

Which type of lab testing is helpful in the detection of antibodies in viral infections?

A

Serology

98
Q

In serology testing, how can you distinguish between acute and chronic infections? (hint: Antibodies)

A

The presence of different isotypes IgM vs IgG can distinuish between acute and chronic infection

99
Q

Which two types of bacteria don’t stain well and are also difficult to culture? What is a better test to diagnose infections with these microorganisms?

A

Chlamydia and mycoplasm infections

Serology

100
Q

What is the main limitation with serology testing, in terms of looking for antibodies?

A

Antibodies can take weeks to develop

101
Q

This lab technique that takes a specific sequence of DNA and amplifies it to be used for further testing. It amplifies dsDNA molecules (fragments) with the same size and sequence by enzymatic method and cycling condition.

A

PCR

102
Q

Four steps of PCR:

1. _______________ by heat

A

Denaturation

103
Q

Four steps of PCR:

2. Annealing ________ to target sequence

A

primer

104
Q

Four steps of PCR:

3. ___________ TAQ DNA polymerase synthesizes in the 5’ to 3’ direction

A

Extension

105
Q

Four steps of PCR:

4. The first PCR cycle ends with _____ new DNA strands that are identical to original target

A

two

106
Q

Which type of laboratory testing in helpful in determining the causative agent in viral encephalitis?

A

PCR

107
Q

PCR testing has a good ___________ predictive value- a high probability that people with a negative test truly DON’T have the disease.

A

negative

108
Q

Which lab technique is used to monitor viral load? (e.g. HIV or HCV)

A

PCR

109
Q

Main limitation of PCR:

Can only be used to identify the presence or absence of a _________ pathogen or gene.

A

known

110
Q

This type of culture may consist of a single cell, a population of cells, or a whole or part of an organ

A

Tissue culture

111
Q

What type of culture is helpful in studying

  1. the cytopathic effects on cells
  2. expression of viral proteins detected at the cell surface
A

Tissue culture

112
Q

What laboratory technique is used to differentiate bacteria by the chemical and physical properties of the cell walls?

A

Gram staining

113
Q

Safranin or fuchsine is the counterstain that shows up as pink or red in what type of bacteria?

A

Gram negative bacteria

114
Q

Name some examples of gram positive bacteria

A
  1. Staphylococcus
  2. Streptococcus
  3. Enterococcus
  4. Listeria
  5. Lactobacillus
115
Q

Name some examples of gram negative bacteria

A
  1. E.coli
  2. Pseudomonas
  3. Chlamydia
  4. Yersinia pestis
116
Q

Acid-fast stains such as Ziehl-Neelsen, or fluorescent stains such as auramine are used to identify what type of bacteria?

A

Mycobacteria

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