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Foundations of Medicine > TBL 11 Bacteria > Flashcards

TBL 11 Bacteria Flashcards

1
Q

Lymphocytes and lymph return to the blood via the ______ duct.

A

thoracic duct

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2
Q

The first line of host defence is the ______ mechanism, which prevent the bacteria/pathogen from infecting the body.

A

barrier mechanism

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3
Q

The first stage of infection by pathogens involve _______ to the epithelium, followed by local infection and _______ of the epithelium.

A

adherence and penetration of epithelium

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4
Q

First line of defence:

The ____ acts as a physical barrier and contains antimicrobial peptides.

A

Skin

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5
Q

First line of defence:
The gastrointestinal tract has (low/high) pH, intestinal motility and intestinal ______ which acts as a biological barrier as it competes with the pathogens for nutrients.

A

low pH; intestinal motility and intestinal flora

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6
Q

First line of defence:

The neurological tissues have a ______ barrier.

A

blood-brain barrier

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7
Q

The second line of host defence is the _____ immunity, which helps to clear most infective organisms, and only those with ________ may survive.

A

Second line of host defence is the innate immunity.

Only those with virulence factors

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8
Q

The innate immunity involves recognition of ______ using pattern recognition receptors which recognise conserved microbial structures such as fimbriae, dsRNA, peptidoglycan.
_____ can also be used as a recognition signal, and this includes inflammation and necrotic cell death.

A

PAMPs and DAMPs

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9
Q

The third line of defence is the _______ immunity, which is mainly mediated by ___ and ___________.

A

adaptive immunity; mainly mediated by B and T lymphocytes.

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10
Q

In the presence of _______ released by CD4+ T cells, B cells can switch their antibody class to provide a more specific immune response, and undergo affinity maturation to increase affinity of antibodies.

A

cytokines

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11
Q

The memory B and T cells formed in response to an infection remain circulating in the _________ and ______, or reside in the ___________, waiting for re-exposure to the same antigen/pathogen.

A

Memory cells remain circulating in the bloodstream and lymph, or reside in the secondary lymphoid organs.

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12
Q

Memory cells allow for:

1) Faster
2) Stronger
3) More specific

secondary response?

A

All

Faster - sensitive to antigens

Stronger - more cells

More specific - undergone affinity maturation

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13
Q

Some pathogens are ________. This can be further divided to being on the epithelial surface, or existing in interstitial spaces, blood or lymph.

A

extracellular

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14
Q

Some pathogens are _________. This can be further divided into cytoplasmic or vesicular.

A

Intracellular

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15
Q

For extracellular pathogens within the interstitial spaces, blood and lymph, the typical immune response includes:

1.
2.
3.
4.

A
  1. Complement activation
  2. Antibodies
  3. Neutrophils and macrophages
  4. Inflammatory reaction
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16
Q

Pro-inflammatory mediators released by macrophages causes the (dilation/contraction) of local small blood vessels and expression of adhesion molecules.
(More/less) white blood cells are produced and enter the bloodstream, then move to the site of infection.

A

Pro-inflammatory mediators cause the dilation of local small blood vessels. More white blood cells are produced.

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17
Q

Innate immunity causes the (increased/decreased) production of chemokines which attract white blood cells to site of infection via _________.

A

increased production of chemokines which attract WBCs to the site of infection via chemotaxis.

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18
Q

________ refers to the leakage of plasma proteins, which occurs due to (increased/decreased) vascular permeability.

A

Plasma exudation; occurs due to increased vascular permeability

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19
Q

Blood clotting may occur in the microvessels to prevent microbial spread in the blood.

A

-

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20
Q

Th17 cells release cytokine _____, which act on fibroblasts or epithelial cells to secrete neutrophil chemotactic proteins to recruit neutrophils and induce production of ______.

A

Th17 release cytokine IL-17; induce production of defensins

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21
Q

Large extracellular parasites trigger _______ and _______ responses.
(like allergic reactions)

A

eosinophils and mast cells

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22
Q

Upon recognition of parasite antigen presented on APCs, ____ cells become activated and secrete cytokines.

IL-4 and IL-13 induce B cell development and differentiation to produce specific anti-parasitic antibody ____ which bind to antigens on the parasite.

A

Th2 cells; antibody IgE

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23
Q

Parasite:

Cytokine ____, which is produced by Th2 cells, will induce terminal differentiation of eosinophils by binding to CCR3 receptor, causing the eosinophil to express specific Fc receptors which recognise the IgE antibodies on the parasite.

A

IL-5

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24
Q

Parasite:
Upon binding to the parasite, mast cells release _______, TNF-a and enzymes. _________ release major basic protein, peroxidases and eosinophil cationic protein.

A

Mast cells release histamine, TNF-a and enzymes.

Eosinophils release…, causing cellular lysis and death of parasite.

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25
Q

The typical immune responses against intracellular pathogens include:

  1. 2.
A
  1. Hyperactivation of macrophages

2. Cytotoxic T cells

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26
Q

For macrophage hyperactivation,
the activated Th_ cells will express CD__ ligand on its surface, which binds to CD__ on the macrophage, and secretes ____, hyperactivating the macrophage.

A

Activated Th1 cells express CD40 ligand which binds to CD40 on the macrophage, and secretes IFN-y, hyperactivating the macrophage.

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27
Q

If the immune system is unable to destroy the intracellular pathogen, it attempts to wall it off and prevent the infection from spreading via _________ formation.

A

granuloma formation

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28
Q

Granuloma formation is an (active/passive) process.

A

Active process; since the constant death of macrophages in the granuloma core require constant turnover by addition of new cells

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29
Q

Viruses often act (intracellularly/extracellularly).

A

intracellularly

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30
Q 
Typical immune response against viruses include:
1.
2.
3.
4.
A
  1. Interferons
  2. NK cells
  3. Cytotoxic T cells
  4. Antibodies
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31
Q

_________ help microorganisms to cause disease and may include toxins or mechanisms for adhesion, uptake, mobility, survival and immunomodulation.

A

Virulence factors

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32
Q

Immune evasion for pathogens:

________ involve pathogens possessing surface structures resembling human molecules, so the immune system mistakes them as “self” and does not attack.

A

Molecular mimicry

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33
Q

Immune evasion:

Many pathogens have different variations of a single antigen, immune system unable to recognise.

A

-

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34
Q

Immune evasion:

Some bacteria living on mucosal membranes cleave antibody ___ using ______ (enzyme) to prevent its activity.

A

Cleave antibody IgA using IgA proteases

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35
Q

_________ contains several pathogenicity islands (SP1/SP2), which encode type III secretion systems used to inject effector molecules into host cells.

A

Salmonella

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36
Q

___ of Salmonella is used to force macrophages to engulf the bacterium, whereas ___ is used to avoid killing within the macrophage.

A

SP1 - force macrophage to engulf bacterium

SP2 - avoid macrophage killing

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37
Q

The type III secretion system is encoded for by (SP1/SP2)

A

SP2

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38
Q

The salmonella bacterium contained within the vacuole can inject different effector molecules into the cytoplasm of the host cell using the type III secretion system to:

  1. Block the intracellular trafficking of ______ and docking to the phagosome, reducing phagolysomal fusion.
  2. Block assembly of _________ such that no oxygen radicals are produced and no macrophage killing.
  3. _________ of MHC class II molecules, tagging them for degradation, causing less antigen presentation by MHC II.
A
  1. Block intracellular lysosome trafficking, reducing phagolysosome formation
  2. Block NADPH oxidase
  3. Ubiquitination of MHC Class II
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39
Q

Shigella is often ingested with food, and are first taken up by __ cells above the Peyer’s patches in the intestine.

A

M cells (designed to take up specific antigens from the gut)

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40
Q

______ (bacterium) rapidly escapes from the phagosome into the cytoplasm, evading the macrophage killing.

A

Shigella

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41
Q

Shigella will replicate and kill the macrophage, becoming released on the ______ surface of the epithelium, leading to massive inflammation induced by macrophages.

A

Shigella is released on the basolateral surface of the epithelium

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42
Q

Shigella can spread laterally from cell to cell without exposing themselves to the immune system, by inducing ____ polymerisation to propel themselves into the next cell.

A

actin polymerisation

Actin tail formation

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43
Q

Immunomodulation by microorganisms include:

  1. Killing of _______ (cells) by leukocidins
  2. Production of _______ which bind TCRs and MHC molecules in the non-variable regions, linking them together and distorting the T cell response
  3. Production of VacA toxin and y-glutamyl transferase to inhibit (cell) activation and proliferation by acting on IL-2 and IL-2 receptors
  4. Induce ____ cells to suppress the immune response
A
  1. Killing of neutrophils by leukocidins
  2. Production of superantigens to distort T cell response
  3. T cell inhibition
  4. T reg cell activation
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44
Q

The _______ in the brain regulates the core temperature of the body using temperature sensors to monitor temperature.

A

hypothalamus

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45
Q

The ________ (POA) and ________ (DMH) are the two important structures in temperature regulation.

A

Pre-optic area and dorsomedial hypothalamus

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46
Q

The maintenance of body temperature relies on sensing the external environment and responding to it, using warmth and cold sensors.

Warmth sensors are unmyelinated __________, whereas cold sensors are _______ and decreased input from ______.

A

Warmth sensors: unmyelinated C-fibres

cold sensors:
A-delta fibres and decreased input from C-fibres

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47
Q

The temperature sensation detected by the sensors enter the spinal cord via the _________, which passes signals to the _________ and finally the hypothalamus.

A

Enter the spinal cord via the A) Lissauer’s tract, which passes signals to the B) lateral spinothalamic tract and finally the C) hypothalamus

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48
Q

Temperature signals from temperature sensors are processed in the ______ and _______

A

POA and DMH in the hypothalamus

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49
Q

When (warmth/cold) sensors in the skin detect increased skin temperature, afferent signals are sent to the POA and DMH which will transmit efferent signals to effector organs to effect a response:

  • Peripheral (vasodilation/vasoconstriction) of skin arterioles to allow greater blood flow to the surface.
  • (Constriction/Dilation) of shunt vessels to force blood to move through the surface of arterioles for cooling.
  • (Increased/decreased) production of sweat
A
  • Peripheral vasodilation of skin arterioles
  • Constriction of shunt vessels
  • Increased sweat production
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50
Q

When (warmth/cold) sensors in the skin detect decreased skin temperature, afferent signals are sent to the POA and DMH which will transmit efferent signals to effector organs to effect a response:

  • Peripheral (vasoconstriction/vasodilation) of blood arterioles to prevent blood flow to the surface
  • (Dilation/constriction) of shunt vessels to allow blood to bypass the surface of arterioles
  • __________ of hairs to trap a cushion of heat-insulating air
  • Metabolism of ___ to help generate heat
  • ________ due to intense muscular spasms to produce heat
A

Warming up:

  • Peripheral vasoconstriction of blood arterioles
  • Dilation of shunt vessels
  • Piloerection of hairs
  • Metabolism of fat
  • Shivering
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51
Q

Temperature variation of core body temperature in humans is primarily regulated by the __________ which project into the POA, allowing for circadian modulation of body temperature.

A

suprachiasmatic nucleus (circadian pacemaker)

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52
Q

Lying down can (increase/decrease) distal skin temperatures, causing a (increase/decrease) in core body temperature.

A

Lying down can increase distal skin temperatures, causing a decrease in core body temperature.

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53
Q

Melatonin is a sleep-related neurohormone that causes peripheral (vasodilation/vasoconstriction) and radiation of heat causing heat (loss/gain).

A

Peripheral vasodilation causing heat loss.

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54
Q

A (increase/decrease) in body temperature and its maintenance overnight is integral to a normal circadian rhythm.

A

decrease

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55
Q

The gold standard for measuring body temperature is to measure the temperature of the blood within the __________.

A

pulmonary artery

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56
Q

Temperature is generally measured at four peripheral sites:

A

Oral, tympanic (ear), rectal, axillary

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57
Q

Fever is when body temperature is raised in the presence of an _________.

A

infective agent

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58
Q

________ fevers are characteristic to TB, abscess, schistosomiasis.

A

Spiking

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59
Q

_______ (diurnal variation) fevers are characteristic to Kawasaki disease, malaria and amoebiasis.

A

Remitting

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60
Q

________ fever (i.e. fever for 7 days then 3 days normal) is characteristic to dengue, Legionnaire’s disease.

A

Saddleback

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61
Q

Longer periodicity fever is characteristic to Pel-Ebstein fever in ________.

A

lymphoma

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62
Q

Infections lead to the release of ______ that will cause the increased production of _____ which will bind to EP3 receptor within the ___ of the hypothalamus, which signals to the DMH, causing a sympathetic activation of non-shivering thermogenesis.

A

Infections lead to the release of pyrogens that will cause the increased production of prostaglandin E2 (PGE2), which bind to EP3 receptor within the POA of the hypothalamus, which signals to the DMH.

TLDR:
Pyrogens –> Production of PGE2 –> bind to EP3 receptor in POA —> signals to DMH –> Sympathetic activation of thermogenesis

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63
Q

There are two main endogenous cytokine pyrogens: ___ and ___.

A

IL-1 and TNF-a

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64
Q

IL-1 and TNF-a enhance breakdown of arachidonic acid into _________, enhancing localised inflammation and induces fever.

A

prostaglandins

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65
Q

____, ____ and ____ may also act as endogenous pyrogens, but to a lesser extent compared to IL-1 and TNF-a.

A

IL-6, IL-8 and IFN-y

66
Q

Exogenous pyrogens are typically associated with ______ infections.

_________ (LPS) is a cell wall component of bacteria and it binds to _____ on the macrophage surface, stimulating macrophages to release IL-1 and TNF-a, effectively leading to the production of endogenous pyrogens.

A

bacterial infections;

Lipopolysaccharides bind to toll-like receptor 4 (TLR4) on macrophages to induce macrophages to release cytokines.

67
Q

LPS in bacteria cross-interacts with TLR4, resulting in activation of a signalling cascade, leading to transcription factor _____ formation in the nucleus.

____ transcription factor upregulates ______ production.

A

Transcription factor NFkB formation

upregulates cytokine production

68
Q

TNF-a and IL-1 are released by immune cells to stimulate other cells to release ____________ proteins which are synthesised by the liver.

A

acute phase proteins

69
Q

________ (acute phase protein) binds free iron.

A

Ferritin

70
Q

_______ (acute phase protein) downregulates ferroportin expression to prevent release of iron from cells.

A

Hepcidin

71
Q

__________ (acute phase protein) oxidises iron to facilitate ferritin action.

A

Ceruloplasmin

72
Q

_______ (acute phase protein) binds haemoglobin.

A

Haptoglobin

73
Q

Acute phase proteins work to bind ____ to proteins or keep it within cells, so that microorganisms have to excess to them. This starves the bacteria.

A

binds iron

74
Q

Bacteria come in three shapes:

Spherical), (Rod-shaped), (spiral-shaped

A

Cocci (spherical)

Bacilli (rod)

Spirochaetes (spiral)

75
Q

Gram-positive bacteria is stained (purple/red) due to the exposed peptidoglycan cell wall that retains the iodine dye.

A

purple

76
Q

Gram-negative bacteria is stained (purple/red) as the outer membrane resists the first dye, and is decolorised by alcohol before absorbing the counter-stain.

A

red

77
Q

Salmonella, Shigella, E. Coli, Vibrio Cholerae and Neisseria are Gram-________ bacteria.

A

Gram-negative

78
Q

Mycobacterium tuberculosis is an _______ bacilli that can resist the gram stains.

A

acid-fast

79
Q

Listeria is an (intracellular/extracellular) pathogen.

A

intracellular

80
Q

Salmonella bacteria is an (intracellular/extracellular) pathogen.

A 
Intracellular 
*It prevents the formation of phagolysosome and NADPH oxidase. Ubiquitination of MDH class II.
81
Q

Salmonella bacterium has a ________ (Structure), allowing it to be propelled forward, aiding its movement towards the host cell.

A

flagella (angular momentum)

82
Q

The ______ secretion system of Salmonella delivers virulence proteins into the host cells, to trigger uptake into epithelial cells, because they are not naturally phagocytic.

This is done by triggering _____ rearrangement and then engulfment of the bacterium.

A

Type III secretion system

Triggers actin rearrangement and then engulfment
(actin polymerisation, membrane ruffling and bacterial internalisation)

83
Q

Listeria (does/does not) possess flagellum. It makes use of the force generated during ____ polymerisation to move.

A

does not have flagellum; makes use of force generated during actin polymerisation to move

84
Q

How does listeria bacterium persist/survive in the cell?

A

Listeria bacteria is able to escape from the endosome into the cytoplasm.

85
Q

_________ makes use of host cell membrane protrusions to spread to another cell, never remaining extracellular to avoid immune detection.

A

Listeria

86
Q

The bacterial genome is made up of ____ genome, which is conserved across the different strains of similar pathogens, and the ________ genome which is obtained from disparate sources.

A

core genome and accessory genome

=> this leads to unexpectedly high levels of variation between genomes of bacterial pathogens

87
Q

_________ of bacteria is the process by which a recipient cell takes up small fragments of naked DNA from the surrounding environment, followed by homologous recombination into the genome.

A

Transformation

88
Q

There are three main processes which facilitate horizontal gene exchange between bacteria, contributing to sources of accessory genes and therefore genetic variation.

A

1) Transformation
2) Transduction
3) Conjugation

89
Q

Only _______ bacterial cells can take up naked DNA from the environment (i.e. undergo transformation) via their ___________ factors.

A

Competent bacterial cells; competence factors

90
Q

___________ of donor DNA fragment occurs with homologous section of the recipient cell’s chromosome.

i.e. some sequence must match.

A

Homologous recombination

91
Q

Pathogens like ______ and Streptococcus make use of transformation.

A

Neisseria

92
Q

Transduction involves the use of _________ to carry bacterial genes from their first host to their second host cell due to errors in the phage reproductive cycle followed by homologous recombination.

A

bacteriophages

93
Q

___________ is the process of transfer of the donor cell DNA to the recipient cell via direct contact between the two cells.

A

Conjugation

94
Q

The donor cell for conjugation possesses a ________ which is present on the transmissible plasmid, and contains genes responsible for sex pilus synthesis.

A

fertility (F) factor

95
Q

Donor cell uses _______ to attach to a recipient cell, forming a temporary cytoplasmic mating bridge, which is the route for DNA transfer.

A

sex pilus

96
Q

__________ (horizontal gene trf) is common in drug resistance interactions.

A

Conjugation

97
Q

Any horizontally acquired DNA that contributes to the virulence of the bacterium is a __________.

A

pathogenicity island

98
Q

Bacteria replicate via ________.

A

binary fission

99
Q

Bacteria is able to evolve rapidly and adapt to new environmental challenges due to:
1)
2)

A

1) High replication rate

2) Mechanisms for horizontal gene transfer

100
Q

Binary fission:

  1. Bacterial chromosome is first attached to the __________.
  2. _________ occurs.
  3. Cell elongates, membrane growth causes the two chromosomes to grow apart.
  4. ______ forms and extends as the cell membrane invaginates.
  5. Invaginating cell membrane and newly formed septum splits the cell into two genetically identical daughter cells. (Cytokinesis)
A
  1. Bacterial chromosome attached to plasma membrane.
  2. DNA Replication occurs.
  3. Cell elongates.
  4. Septum formation
101
Q

__________ of bacteria allows for any new genes mutated/taken up by the cell to be expressed in the phenotype immediately.

A

Haploid genome

102
Q

_________ is preventing disease before an infection is acquired, whereas therapy is treating disease after the host is infected.

A

Prophylaxis

103
Q

(Active/passive) immunisation is the administration of antigen, to provoke a host immune response.

A

Active

104
Q

Passive immunisation is the administration of ________ to provide an immediate protection. This includes transfer of antibodies across the placenta, and in breast milk.

A

Antibodies

105
Q

There are mainly two types of vaccines.

A

Live attenuated vaccines

and

Inactivated vaccines

106
Q

Dead whole cell vaccines can be inactivated by ______ or ______ treatment.

A

heating or formalin treatment

107
Q

Subunit vaccines usually require ______.

A

adjuvants (to activate the innate immune system) because there are no danger signals provided by the subunit vaccine itself

108
Q

Attenuation of live viruses is usually done by:

A

Culturing them for many generations in cell lines which are NOT the primary target of the virus

109
Q

Examples of live attenuated vaccines:

A

Oral polio vaccine, BCG vaccine for TB bacterial, measles vaccine, chickenpox vaccine, MMR

110
Q

New way of attenuating viruses:

A
  1. Clone and sequence to identify functions of different genes
  2. Delete/modify a gene by mutations to construct a vaccine with immunogenic surface molecules but no virulence factors
111
Q

_______ is an example of a vaccine obtained from the new way of attenuating viruses.

A

Rotavirus

112
Q

The Dukoral oral cholera vaccine is a (live attenuated/inactivated whole cell/subunit) vaccine.

A

inactivated whole cell vaccine containing killed cholera bacteria and the B component of the cholera toxin

113
Q

There are mainly three types of subunit vaccines.

A

Toxoids, viral surface antigens and bacterial capsule polysaccharides

114
Q

Bacterial capsule polysaccharides vaccine alone with trigger the T-cell (independent/dependent) response.

A 
T-cell independent response
=> No immunological memory and no Ig class switching (only IgM produced)
115
Q

Bacterial lipopolysaccharide LPS vaccine is usually conjugated with a protein to create a _______ vaccine. This can activate T-cell (independent/dependent) response, and therefore form immunological memory and facilitate Ig class switching.

A

conjugate vaccine;

to activate T-cell dependent response

116
Q

There are two main routes of delivery for vaccines.

A

Mucosal or Systemic

117
Q

Vaccines delivered using the mucosal route include two ways.

A

Oral and intranasal

118
Q

For mucosal vaccines, resulting effector cells will home back to mucosal sites, and induce antibody ____ production.

A

IgA

119
Q

For systemic vaccines, there are two ways to deliver it.

A

Intramuscular and Subcutaneous

120
Q

Systemic vaccines result in responses in draining lymph nodes, giving rise to serum antibodies and __________.

A

Circulating cytotoxic T cells

121
Q

Adjuvants are used to activate _______ cells to make them more effective at presenting antigens to T-cells.
It therefore targets the innate immunity to activate the adaptive immunity.

A

Dendritic cells

122
Q

Adjuvants need to be structurally similar to ______ or ______ to activate the innate immune response.

A

PAMPs or DAMPs

123
Q 
For systemic (parenteral) vaccines, common adjuvants use include (A) \_\_\_\_\_\_\_\_\_\_ to fake necrotic cell death signals, 
(B) Oil in water emulsions with surfactants and squalene to induce \_\_\_\_\_\_\_\_\_ and used for antigen retention within injection site, (C) Bacterial products that act directly on PRRs
A

(A) Aluminium salts to fake necrotic cell death

(B) Oil to induce inflammation and used for antigen retention

(C) Bacterial components to act on PRRs

124
Q

__________ is the sum of individual immunities and the effect of lower transmission rate.

A

Herd immunity

125
Q

____ herd immunity in the UK uses vaccination in young children to protect older age groups.

A

HIB (Haemophilus influenza type B)

126
Q

There are two types of polio vaccines. State each type as well as its type of vaccine.

A

Oral polio vaccine (live, attenuated)

Inactivated systemic polio vaccine

127
Q

The disadvantage of inactivated systemic polio vaccine is:

A

It does not give any intestinal immunity as polio is a faeco-oral disease which may replicate asymptomatically in carriers.

128
Q

Bacterial infections arise from ______ (carried by the host) or ______ (External) sources and enter through different portals of entry.

A

Intrinsic VS. Extrinsic

129
Q

Infections targeting the upper respiratory tract are usually (intrinsicially/extrinsicially) acquired from respiratory tract droplets or airborne.

A

extrinsically acquired

130
Q

How does the following bacteria enter the body?

Strep pneumoniae, strep pyogenes, neisseria meningitidis, MRSA, MSSA (S. aureus)

A

Upper respiratory tract infection

131
Q

Urogenital tract infections may enter the body through the urogenital tract, and may be extrinsicially or intrisincially acquired.

A

-

132
Q

Intrinsic infections of the urogenital tract can come from either the __________ and or the _______.

A

large intestine or throat

133
Q

Strep Group A is intrinsically acquired in the _______ and may enter the body through the __________ during pregnancy.

A

Strep Group A is intrinsicially acquired in the throat and may enter the body through the urogenital tract during pregnancy.

134
Q

E. coli and Strep group B are intrinsically acquired in the _________ and may enter the body through the ________.

A

Strep group B and E.coli are intrinsicially acquired in the large intestine and may enter the body through the urogenital tract.

135
Q

______ infections refer to the infections derived from the hospital.

A

Nosocomial

136
Q

Neisseria gonorrhoeae and treponema pallidium are sexually-transmitted infections that can enter the body through _________.

A

urogenital tract

137
Q

The gastrointestinal tract, also known as the _________ route, is a common portal of entry for many pathogens which are usually extrinsicially acquired via contaminated food and water.

A

faeco-oral route

138
Q

How does the following bacteria enter the body?

E.coli, Shigella, Vibrio cholera, Listeria, Salmonella

A

faeco-oral route via the GI tract

139
Q

Bacteria may be classified as _______ which cause disease, or _______ which do not cause disease.

A

pathogens - cause disease; commensals - do not cause disease

140
Q

Pathogens may be further classified into ____ pathogens (infectious agents that cause disease in any host) or _________ pathogens (potentially infectious agents that rarely cause disease in individuals with a healthy immune system).

A

true pathogens VS. opportunistic pathogens

141
Q

The _________ of a bacterium is defined as its ability to cause disease.

A

pathogenicity

142
Q

Pathogenicity of bacteria is affected by
1)
2)

A

1) Infectivity (infection)

2) Virulence (features enhancing disease causation)

143
Q

The higher the infectivity of a bacterium, the (lower/higher) its infectious dose.

A

lower

infectious dose is the average number of bacteria needed to initiate an infection

144
Q

The infectivity of the bacterium depends on several factors:

5

A
  1. Route of transmission
  2. Ability to colonise host
  3. Tropism and motility
  4. Replication speed
  5. Immune evasion
145
Q

________ is when the bacteria enters the bloodstream to cause disease in other parts of the body.

A

Bacteraemia

146
Q

Mycobacterium tuberculosis has a low infective dose and very low replication rate, because it can:

A

survive inside macrophages and resist killing it

147
Q

Vibrio cholerae has very (low/high) infectivity. Therefore it needs flagella for motility.

A

low infectivity (high infective dose)

148
Q

The _________ of a bacteria refers to the features which it possesses that enhance infection and disease causation.

A

virulence

149
Q

Strep pneumoniae - 2 virulence factors

1) Toxin production: _________ is a cholesterol-dependent pore-forming toxin which affects lung architecture, making it more porous for bacteria.
2) Degradation of host molecules: _________ degrades host hyaluronic acid matrix for nutrition and spread.

A

1) Toxin production: Pneumolysin

2) Degradation of host molecules: Hyaluronan lyase

150
Q

Staph aureus:

1) Interference with host cell function: __________ interferes with normal T cell function, which may cause organ failure.
2) Immune evasion: _________ lead to neutrophil death and abscess formation.

A

1) Superantigens

2) Leukocidins

151
Q

Strep pyogenes is a mouth bacteria that will cause _________.

A

tonsilitis

152
Q

Neisseria meningidis colonises the nasopharynx asymptomatically before invading the epithelial and endothelial cells to enter the bloodstream, causing ____________.

A

Meningococcal septicaemia (bloodstream infection)

153
Q

Pneumonia is caused by bacteria _______,.

A

Strep pneumoniae

154
Q

Cholera is caused by pathogen __________, which is transmitted using the ______ route.

A

Vibrio cholerae; faeco-oral route

155
Q

_________ colonises the maternal genital tract from the GI tract, which can cause invasive GBS infection in neonates, causing disease _________.

A

Group B Strep; Neonatal meningitis septicaemia

156
Q

Strap aureus produces a family of leukocidins which destroy neutrophils, causing ______.

A

abscess

157
Q

Vibrio cholerae has a low infectivity, which uses its _____ to penetrate the thick mucus layer in the intestines, and hooks to the intestinal walls.

A

flagella

158
Q

Vibrio cholerae:

  1. Synthesises toxin A and B to bind to the _______ on the gut wall
  2. Retrograde endocytosis of toxin ___
  3. Binding of toxin A to ___ proteins stimulate _______ to produce cAMP
  4. cAMP activates the ________ channels in the membrane, causing…
A
  1. Toxins A and B bind to GM gangliosides on the gut wall.
  2. Retrograde endocytosis of component A
  3. Binding of toxin A to Gas proteins stimulate adenylyl cyclase to produce cAMP
  4. cAMP activates CFTR chloride channels in the membrane, causing Cl- efflux from the cell, allowing Na+ and water to leave the cell.
    => Diarrheoa and dehydration
159
Q

Staph and strep and listeria are (gram-negative/gram-positive) bacteria.

A

gram-positive

160
Q

Neisseria, HIB, E.coli, salmonella, Vibrio cholera and Shigella are (gram-negative/gram-positive) bacteria.

A

gram-negative

161
Q

Pseudomonas aeruginosa and Acinetobacter baumanii are examples of (Gram-positive/gram-negative) ____________.

A

Gram-negative opportunistic pathogens

162
Q

Staph epidermis and Enterococcus faecalis are examples of (Gram-negative/Gram-positive) ____________.

A

Gram-negative opportunistic pathogens

Foundations of Medicine (21 decks)

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