From encounter to disease - Bacteriology I Flashcards
Contains the lectures from Willem and about pneumococcal infections
1
Q
What is a factor to determine if bacteria are primitive?
A
Organization the cell itself
2
Q
What are two-component systems?
A
Systems that carry out signal transduction
3
Q
What are the two proteins of the two-component regulatory system
A
- Sensor kinase
- Response regulator
4
Q
What is the function of a sensor kinase?
A
Detects environmental signal and autophosphorylates
5
Q
What is the function of a response regulator?
A
DNA-binding protein that regulates transcription
6
Q
Describe the possibility of the dual function of response regulators
A
Response regulator can be activating and inhibitory of the RNA polymerase –> transcription activated/inhibited
7
Q
How many two-component systems can be found in E.coli?
A
50
8
Q
Examples of two-component systems in E.coli
A
- Phosphate assimilation
- Nitrogen metabolism
- Osmotic pressure response
9
Q
Describe the osmotic component system in E.coli
A
10
Q
What are two-component systems important for?
A
Monitoring and responding to changes in the bacterial environment
11
Q
Can you see a Campylobacter under your microscope if they are active? Why/why not?
A
No, they are way too fast. You have to numb them.
12
Q
What happens to the movement of bacteria if there is a absence/presence of attractants in their surroundings?
A
Absence: random movement
Presence: directed movement
13
Q
Why two kinds of movement are there for flagellated bacteria?
A
- Peritrichous
- Polar movement
14
Q
How does peritrichous movement work?
A
- Bundled flagella (CCW rotation). —>
- Flagella pushed apart (CW rotation) <—>
- Flagella bundled (CCW rotation) <—
15
Q
Which division is important to make in polar movement of flagellated bacteria?
A
If a bacterium has a reversible- or unidirectional flagella
16
Q
Orientation of movement of bacteria with: one flagella
A
Can move their flagella clockwise or counter clockwise
17
Q
How does polar movement for bacteria with reversible flagella work?
A
- CCW rotation —>
- CW rotation <—
18
Q
How does polar movement for bacteria with unidirectional flagella work?
A
- CW rotation —>
- Cell stops, reorients
- CW rotation upwards
19
Q
How do they sense their surroundings?
A
Two component system used in chemotaxis
20
Q
How is the two-component system used in chemotaxis? (3)
A
- Sense temporal changes in attractants or repellents
- Regulate flagellar rotation
- Regulate activity of pre-existing proteins
21
Q
Definition of taxis
A
Directed movement in response to chemical or physical gradients
22
Q
Different kind of ‘taxes’ (5)
A
- Chemotaxis - chemicals
- Phototaxis - light
- Aerotaxis - oxygen
- Osmotaxis - ionic strength
- Hydrotaxis - water
23
Q
True or false: “Bacteria can actively search for targets”
A
True. Chemotaxis
24
Q
What are endospores?
A
Survival structures to endure unfavorable growth conditions
25
Why are endospores perfect for bacteria that don't have a flagella?
This ensures a perfect way to be spread
26
How are endospores spread?
Ideal for dispersal via wind, water, or animal gut
27
In what kind of bacteria can you find endospores?
Present only in gram-positive bacteria, (e.g., Bacillus and Clostridium)
28
Describe the sporulation stages (7)
- Normal division
- Commitment to sporulation --> asymmetric division
- Spore is formed in the bug
- Forms all kind of covers and stuff to penetrate materials
- Bacterial cell lyses
- Free endospore
- Germination
29
Name an example of a disease that can occur due to endospores
Antrax infection in the lungs
30
What does the endospore package contain?
DNA needed to form a new bacterium
31
Describe the maltose catabolism in E.coli
Protein needs to bind maltose to form a complex on the activator site, RNA polymerase can bind --> machinery to metabolize maltose
32
What is catabolite repression?
Global regulating system: controls use of carbon sources if more than one presents
33
Catabolite repression is also called the "glucose effect". Why?
Because the synthesis of unrelated catabolic enzymes is repressed if glucose is present in growth medium
34
What is diauxic growth?
Two exponential growth phases if two energy sources are available
35
35
How does diauxic growth work?
- Better energy source consumed first, growth stops
- After lag, growth resumes with second energy source
36
What controls transcription in catabolite repression? How?
Cyclic AMP receptor protein. CRP binds to DNA only if it has bound cyclic adenosine monophosphate
37
How is the inactive repressor generated to make lactose?
- CRP/cAMP binds to operator and blocks transcription
- Lacl is transcribed and translated
- Active repressor
- Inducer binds to AR
38
Catabolization of a certain sugar by a bacterial cell depends on... (2)
- Presence of the metabolite
- Metabolic status of the cell
39
What can influence the presence of a metabolite?
Presence of other sugars
40
What is quorum sensing?
Mechanism by which bacteria assess their population density
41
What does quorum sensing ensure?
That a sufficient number of cells are present before initiating a response that, to be effective, requires a certain cell density
42
Name an example of a virulence factor of 'E.coli O157:H7 shiga toxin–producing strain' involved in quorum sensing?
Produces AHL AI-3 that induces virulence genes
43
What does AL-3 bind to and where?
Sensor molecules in plasma membrane.
44
What is the result of AL-3 binding to sensor molecules in the plasma membrane? (3)
Activation of
- Motility
- Toxin secretion
- Production lesion-forming proteins
45
Name an example of a virulence factor of S.Aureus involved in quorum sensing?
Secretes small peptides that damage host cells or alter host's immune system
46
What controls this secretion of small peptides in S.Aureus?
Autoinducing peptide (AIP)
47
What are potential drugs preventing virulence gene expression?
Quorum-sensing disruptors
48
What are stringent responses?
Stress response in reaction to amino acid starvation
49
Name an example of a stringent response in E.coli?
Voiding E. coli in feces reduces nutrients -->initiates ppGpp synthesis --> arrested cell division
50
Name an example of a stringent response
Lungs hypoxic and phosphate-limited
51
Function of the TATA box
Stable binding on the promoter
52
Name two global control systems
- Heat-shock response
- RpoS regulon
53
What is the function of the heat-shock proteins?
Counteract damage of denatured proteins and help cell recover from temperature stress
54
How are heat-shock proteins induced?
Induced by heat, exposure to ethanol or ultraviolet (UV) radiation
55
What factor largely controls the heat-shock response?
Alternative sigma factor RpoH
56
What factor largely controls the RpoS regulon?
Stationary phase sigma factor
57
What kind of infections can be caused by Streptococcus bacteria?
- Pneumonia
- Meningitis
- Otitis media
58
What kind of bacterium is S. pneumonia?
Gram-positive, microaerophillic coccoid bacterium (diplococcus)
59
Describe the lifecycle of S. Pneumonia (3)
- Colonization of epithelium
- Transmission/Shedding
- Invasion
60
Where does colonization of S. Pneumonia happen?
Nasal epithelium
61
Describe the three options of invasion of S. Pneumonia
- Aspiration (lungs)
- Bacteraemia (brain)
- Local spread (ear)
62
How can the general epidemiological curve of incidence be described? (pneumococcal infections)
U-curve (infants and elderly)
63
Which factor can really influence the epidemiological curve?
Co-infection
64
Which factors play a role in the onset of a co-infection? (4)
- Epithelial cell damage
- Decreased mucociliary velocity
- Reduced CCL2 expression
- Reduced macrophage functionality
65
How can you perform an etiological diagnosis of pneumococcal infections? (4)
- Isolation from URT, blood, sputum, CSF
- Culture and characterization
- PCR/MALDI-TOF
- Bile solubility test
66
What is the transformation principle?
DNA crossed over from the virulent strain to the non-virulent strain
67
Advantage of the pneumococcal capsule
Capsule protects bacterium in the bloodstream against the immune system --> resistance against phagocytosis
68
Describe the biosynthesis of the polysaccharide capsule
- Every sugar structure has repeating units
- New sugar that has to be added (specific for sugar) is flipped outside and attached to peptidoglycan
69
Techniques used to determine genetic variation amongst S. Pneumonia? (2)
- Multi-locus sequence typing
- Whole genome sequencing
70
How can a non-competent cell become competent? How is competence induced?
Horizontal gene transfer induced by environmental signals (high cell density, stress)
71
What does competence lead to?
Killing of neighboring cells
72
Which proteins can be found in the pneumococcal cell wall? (4)
- Phosphorylcholine binding proteins
- Peptidoglycan binding proteins
- Classical surface proteins
- Lipoproteins
73
What is the function of ABC transporters?
Niche adaptation
74
What is essential for the induction of inflammation? What does this phenomenon lead to?
Pore formation. Leads to faster clearance and increased transmission
75
Which additional factors influence transmission if you are a nasal carrier of S. pneumonia? (5)
- Pneumolysin
- Capsule type and amount
- Anticapsule IgG
- Anticapsule IgA1
- Viral co-infections
76
Function of pneumolysin in transmission of s.pneumonia? (2)
- Increased shedding
- Inflammation promotes secretions
77
Capsule type amount
- Increased shedding
- Inhibition of mucin entrapment
78
Anticapsule IgG
- Decreased shedding
- Agglutionation blocks release
79
Anticapsule IgA1
- No effect on shedding
- Bacterial protease relieves agglutination
80
Viral co-infection
- Increased shedding
- Increased bacterial load and mucus production
81
Which factors influence the prominence of S. pneumonia as a cause of disease? (3)
- High carriage rates
- Genetic adaptability
- Ability to shift from commensal to pathogenic interaction with host
82
From colonisation to invasive disease requires niche adaptation. Name two ways of niche adaptation
- Metabolic adaptation
- Immunological adaptation
83
What is meant with metabolic adaptation?
Maintenance of metal levels, different carbon sources
84
What is meant with immunological adaptation?
From non-sterile to sterile site
85
