Session 5 Flashcards
(123 cards)
1
Q
Is C.difficile an aerobic or anaerobic bacteria?
A
Anaerobic
2
Q
What antibiotic is commonly used for treatment of C difficile?
A
Metronidazole
3
Q
C. difficile is a part of the commensals of which pat of the body?
A
Gut
4
Q
What type of bacteria is Staph aureus?
A
Gram positive
Coccus
5
Q
Staph aureus is found normally in which parts of the body?
A
Skin
Nasopharynx
6
Q
Staph aureus is particularly common in causing infections in which part of the body?
A
Skin - e.g. Cellulitis
7
Q
What antibiotic is common given for Staph aureus infections?
A
Penicillins - e.g. FLUCLOXACILLIN
8
Q
What is pus composed of? (5)
A
Dead/dying WBCs Cellular debris Serous fluid Fibrin Bacteria
9
Q
What is an abscess?
A
A collection of pus commonly caused by a bacterial infection
10
Q
Staph aureus commonly results in _____________ formation
A
Abscess
11
Q
What effect does Staph aureus have on WBCs and RBCs?
A
They lyse WBCs and RBCs in the infection area
12
Q
What does lysis of neutrophils by staphylococcus aureus result in?
A
The pouring out of large amounts of lysosomal enzymes which damage the surrounding tissue
13
Q
What does Staphylococcus aureus release to cause the lysis of neutrophils and RBCs?
A
Leukocidin
Haemolysins
14
Q
What does MRSA stand for?
A
Methicillin resistant Staph aureus
15
Q
MRSA is resistant to which class of antibiotics?
A
All b-lactam antibiotics
16
Q
What does MRSA produce that gives it resistance to b-lactam antibiotics?
A
Penicillin binding protein 2a
17
Q
Is MRSA found in healthy people?
A
Yes, as with other staphylococci - a % of the population is harmlessly colonised by MRSA
18
Q
How is MRSA usually spread?
A
Skin-to-skin contact
Also through towels, sheets etc. of someone with MRSA
19
Q
Does MRSA survive for a long time on surfaces (e.g. Door handles)?
A
Yes
20
Q
What is the recommended treatment for invasive MRSA?
A
Vancomycin
21
Q
What class of antibiotics does vancomycin belong to?
A
Glycopeptides
22
Q
Can vancomycin be given intravenously?
A
Yes
23
Q
What is considered to be the most important measure to reduce the spread of MRSA in the health care setting?
A
Hand hygiene
24
Q
What type of virus is norovirus?
A
Non-enveloped, single stranded RNA virus
25
Norovirus is a major cause of which outbreaks?
Outbreaks of acute gastroenteritis
26
What is the treatment for norovirus?
No specific treatment - supportive measures
27
How is norovirus mainly transmitted?
Faecal-oral
| Also respiratory
28
Define healthcare infections
Infections arising as a consequence of providing healthcare
29
To be defined as a healthcare infection, onset has to be at least ______ hours after admission
Why is this?
48
To allow for the incubation period of the infection
30
As well as affecting patients, healthcare infections can also affect...
Hospital visitors
| Healthcare workers
31
Give an example of common healthcare ...
I) Viruses (2)
II) Bacteria (2)
III) Fungi (2)
IV) Parasite (1)
Norovirus, Hep B, Hep C, HIV
MRSA, C diff, E. coli
Candida albicans
Aspergillus species
Malaria
32
Name some patient factors that result in increased risk of acquiring infections
```
Extremes of age
Diabetes
Smoker
Cancer
Obesity/Malnourished
```
33
What are the 4 P's of infection prevention and control?
Patient
Pathogen
Practice
Place
34
How is antimicrobial prophylaxis administered before surgery?
A single dose is given just before surgery - a sufficient concentration required for the length of time the incision is open
35
What is commonly given as a preventative measure for Staph aureus?
Mupirocin nasal ointment
36
Give an example of a 'physical barrier' involved in the isolation of infected patients
Positive pressure rooms
37
All healthcare workers are immunised against _________ as it is very infectious
Hep B
38
What does PPE stand for in regards to infection prevention?
Personal protective equipment - e.g. Aprons, gloves
39
The immune system can recognise/distinguish between which 2 types of microbes...
Extracellular microbes
| Intracellular microbes
40
Extracellular microbes divide __________ the cell
Intracellular microbes divide ____________ the cell
Outside
Inside
41
Intracellular microbes are usually...
Viruses
42
Name the three stages of how an APC works
Capture
| Processing presentation
43
The main job of APCs is to...
Present antigens to the cells of the adaptive immunity (T cells)
44
APCs are found in strategic locations such as...
| 4
Skin - SALT
Mucous Membranes MALT - GALT, NALT, BALT, GUALT
Lymphoid organs
Blood circulation
45
Give two examples of lymphoid organs
Lymph nodes
| Spleen
46
What is macropinocytosis?
Ingestion of soluble particles by cells - e.g. Toxic chemicals released by microbes
47
Adaptive immunity can be split into...
Humoral immunity
| Cell dependent immunity
48
Humoral immunity acts through...
Antibodies circulating in the fluid
49
Cell-mediated immunity acts through...
Phagocytosis or cytotoxicity
50
What is the primary target of the humoral immunity?
Extracellular pathogens (bacteria)
51
What is the primary target of the cell mediated immunity?
Intracellular pathogens (viruses)
52
Extracellular pathogens are usually...
Intracellular pathogens are usually...
Bacteria
Viruses
53
Name 4 APCs
Dendritic cells
Langerhans cells
Macrophages
B cells
54
In what locations of the body are dendritic cells usually found?
What type of cells do dendritic cells present to?
Lymph nodes
Mucous membranes
Blood
Naive T cells
55
Where are Langerhans cells typically found in the body?
What cells do Langerhans cells usually present to?
Skin
Naive T cells
56
Where are macrophages typically found in the body?
Which cells do they present to?
In various tissues
Effector T cells
57
Where are B cells typically found in the body?
What cells do they present to?
Lymphoid tissues
Effector T cells
Naive T cells
58
What are naive T cells?
Cells that have not yet been activated by an APC or exposed to an antigen
59
What are effector T cells?
Cells that have already been activated by an APC besides macrophages/B cells
60
What are PAMPs?
What are they recognised by?
Pathogen Associated Molecular Patterns
Microbes have PAMPS which can be recognised by the PRRs on APCs
61
How are the APCs processing the different antigens able to activate the right response?
Through the action of a set of proteins called MHCs - major histocompatibility complex
62
What does MHC stand for?
Major histocompatibility complex
63
Antigen presentation is carried out by which set of proteins?
MHC
64
Name three features of the humoral immunity
Antibodies
Complement
Phagocytosis
65
Name three features of the cell dependent immunity
Cytotoxic T lymphocytes
Antibodies
Macrophages
66
Name two types of MHC molecules
Class I molecules
| Class II molecules
67
Where are class I MHCs found?
Found on all nucleated cells
68
Where are class II MHCs found?
Dendritic cells
Macrophages
B cells
ONLY APCs
69
MHC-I is found on all nucleated cells and is central to anti-________ immunity
Viral
70
All MHCs are coded for by...
The p arm of chromosome 6
71
What features of MHC molecules ensures an increased number of different/diverse MHC molecules?
There is co-dominant expression of the genes coding for MHC molecules - both parental genes are expressed
72
The genes coding for MHCs are polymorphic, what is meant by this?
Different alleles exist exist among different individuals ---> increased presentation of different antigens/microbes
73
MHC class I molecules present peptides from ____________ microbes
MHC class II microbes present peptides from ____________ microbes
Intracellular
Extracellular
74
Describe the structure of a MHC class I molecule
4 subunits - a1, a2, a3, B2
Peptide binding cleft between subunits a1 and a2
75
Describe the structure of a MHC class II molecules
4 subunits - a1, a2, B1, B2
Peptide binding cleft found between a1 and B2 subunits
76
Where is the peptide binding cleft found on...
I) MHC Class I Molecules
II) MHC Class I Molecules
Between a1 and a2 subunits
Between a1 and B1 subunits
77
The peptide binding cleft of MHC molecules are variable regions with highly polymorphic residues.
What happens here?
Big microbe is processed into small peptides before being presented
78
Are many or few peptides presented by the same MHC molecule?
Many peptides
79
Which T cells recognise MHC class I molecules?
CD8+ T cells
80
Which T cells recognise MHC class II molecules?
CD4+ T cells
81
Which MHC molecule can present slightly shorter peptides?
MHC Class I
82
APCs often express which MHCs?
Both MHC class I and MHC class I - (they are nucleated)
83
Name two antigen processing pathways
Endogenous pathway
| Exogenous pathway
84
Which cells carry out the endogenous pathway of antigen presentation?
All cells
85
Which microbes are targeted by the endogenous pathway of antigen processing?
Intracellular microbes (viruses)
86
Which MHC molecules/T cells are involved in the endogenous pathway of antigen processing?
MHC Class I
CD8+
87
What happens in the endogenous pathway of antigen processing?
Proteasome degrades any ubiquitin labelled proteins in the cytoplasm (self or non-self)
Proteasome produces small antigenic peptides
Antigenic peptides transported in the ER via TAP1 and TAP2 transporters
MHC class I proteins are produced all the time - once there is the right match between the self antigen/viral peptide and MHC class I molecules
Once there is a match the MHC class I/antigen complex is moved to the cell membrane and expressed
88
Which proteins are degraded by proteasome in the endogenous pathway of antigen processing?
Any ubiquitin labelled proteins (self or non-self)
89
How are antigenic peptides produced by the action of proteasome transported into the ER in the endogenous pathway of antigen processing?
Via specific transporters - TAP1 and TAP2
90
The exogenous pathway of antigen processing takes place in which cells?
APCs
91
The exogenous pathway of antigen processing targets which microbes?
Extracellular microbes
92
Which MHC molecules/T cells are involved in the exogenous pathway of antigen presentation?
MHC Class II
CD4+ T cells
93
Describe the exogenous pathway of antigen presentation
Microbe is engulfed and fuses with lysosome
Degradation of microbe into antigenic peptides
The endosome containing the antigenic peptides fuses with a vesicle containing MHC class II molecules
Match between the antigenic peptide and right MHC class II molecule made
Complex expressed at cell membrane
94
What happens to antigenic peptides that do not find an MHC class II match in the exogenous pathway of antigen processing?
They are degraded
95
In the exogenous/endogenous pathways of antigen processing/presentation are both self and non-self peptides presented?
Yes
96
Both self and non-self peptides are presented in the endogenous/exogenous pathways.
How do T cells not respond to self proteins?
They are trained during their development not to react to self proteins
97
All peptides from the same microbe are presented by _______________ MHC molecules
Different
98
In HIV, you will see a reduction in the number of which type of T cell?
CD4+ T cells
99
Why can some individuals test positive for HIV but their CD4+ cell count be normal/viral load be low?
Some patients are called elite controllers and can control viral replication
100
How is an effective T cell response achieved against HIV in elite controllers?
MHC molecules in elite controllers present key peptides that are essential for the survival of the virus
101
Why is there typically a poor T cell response to HIV in most individuals?
MHC molecules present mutated peptides of the HIV virus that aren't critical for the survival of the virus
102
What are two clinical problems associated with MHC molecules
Organ transplant rejection
| Autoimmune disease
103
What happens to cause organ transplant rejection with regards to MHC molecules?
There is a mismatch between donor and recipient MHC molecules
104
Graft-Versus-Host reaction is commonly associated with...
What happens in GVH?
Bone marrow transplant
Immune cells in the donated tissue recognise the recipient as non-self
105
Name an autoimmune disease associated with MHC molecules
Ankylosing spondylitis
106
Extracellular microbes are dealt with by the ____________ immunity. Microbes are processed via ___________ pathways and presented with __________ molecules which are recognised by ________ T cells
Humoral
Exogenous
MHC Class II
CD4+ T cells
107
Intracellular microbes are dealt with by the ________________________ immunity. Microbes are processed by the ____________________________ pathways and presented with ___________ molecules. Which are recognised by ___________ T cells.
Cell-dependent
Exogenous/endogenous
MHC Class I/MHC Class II
CD8+ T Cells/CD4+ T Cells
108
Can cytotoxic T cells be activated without CD4+ T cells?
What is evidence for this?
No
In patients with HIV - there is a low CD4+ cell count and low action of cytotoxic T cells
109
Where are T lymphocytes produced? Where are they matured?
Bone marrow
Thymus
110
How do T cells recognise antigens?
Through specific TCRs - T cell receptors
111
CD4+ T cells are also known as...
T helper cells
112
CD8+ T cells are also known as...
T killer cells
113
T cells are categorised based on...
The cytokine they produce
114
Describe the general structure of a TCR
Consists of a variable and a constant region
115
Cytotoxic T lymphocytes kill target infected cells by the action of which chemicals?
Perforins
| Granzymes
116
Eosinophils are involved in the killing of ____________
Parasites
117
Mast cells particularly produce which immunoglobulin?
IgE
118
Name 4 immune functions of IgG
Fc-dependent phagocytosis
Complement activation
Neonatal immunity
Toxin/virus neutralisation
119
Name 1 immune function of IgA
Mucosal immunity
120
Name two immune functions of IgE
Immunity against Helminths
| Mast cell degradation (allergies)
121
Name one function of IgM
Complement activation
122
Extracellular pathogens trigger the _____________ immunity
Humoral
123
Intracellular pathogens trigger the ______________________ immunity
Cell-mediated
