Microorganisms and Infections Flashcards
(84 cards)
1
Q
Mycoplasma -
Important feature and disease
A
Important feature: Lacks cell wall
Disease - Pneumonia
2
Q
Virus - living cell or not ?
A
Not a living cell - cant replicate unless present in a living cell
3
Q
List 2 types of Fungi with 3 points
A
- Candida albicans
- A yeast
- Unicellular
- Reproduce by budding - Aspergillus fumigatus
- A mould
- multicellular
- Reproduce by spores
4
Q
What is Plasmodium falciparium
A
Protozoa
is a malaria parasite
5
Q
What are Helminths and give 2 examples
A
Eukaryotic cells like Protozoa and Fungi.
Example
- African eye worms
- beef Tape worm
6
Q
What is taxonomy
A
Classification of organism
7
Q
How are organisms named
A
Binomial nomenclature:-
Genus (like surname) first
Species (like given name) second
In italics or underlined
8
Q
Are bacteria prokaryotes of Eukaryotes
A
Prokaryotes
9
Q
List 5 differences between a Prokaryotic cell and a Eukaryotic cell
A
Prokaryotes vs Eukaryotes
No nucleus/membrane bound organelles vs membrane bound nucleus
Haploid vs Diploid
single circular DNA vs chromosome in nucleus
70S ribosome (30S and 50S subunits) vs 80S ribosome (40S and 60S subunits)
Peptidoglycan cell wall vs No cell wall (except plant and fungi)
10
Q
Bacteria morphology
List 2 ways bacteria are classified
A
- by their Shape
2. Staining
11
Q
List 5 bacteria morphology shapes
A
- Round - Coccus
- Long - Bacilli
- Branched - filamentous
- Spiral- spirillum/spirochete
- Comma- Vibro
12
Q
Staining depends on
A
How much peptidoglycan is present in the cell wall
13
Q
List the 5 stages of staining and the end results
A
- Fixation
- Crystal violet
- Iodine
- Ethanol (Decolorization)
- Safranin
If Pink = Gram negative
if Purple = Gram positive
14
Q
Match the following
Clusters, Chain, Strepto-, Staphylo-
A
Clusters = Staphylo- Chains = Strepto-
15
Q
3 types of bacteria based on atmosphere
A
- Anaerobes
- Anaerobes
- Facultative anaerobes- (can switch between aerobic and anaerobic metabolism)
16
Q
List 3 bacterial growth requirements
A
- Temperature
- Salt content
- pH
17
Q
Name 2 examples of Gram positive cocci bacteria
A
- Staphylococcus aureus
2. Streptococcus pyogenes
18
Q
Name and example of Gram negative bacilli bacteria
A
Clostridium difficile
19
Q
Name an example of Gram negative cocci bacteria
A
Neisseria meningitidis
Neisseria gonorrhoea
20
Q
Name 3 examples of Gram negative bacilli
A
Enterobacteriacie
- Salmonella & shigella
- E. Coli
- Klebsiella & Enterobacter
21
Q
Name 2 bacteria without cell walls
A
- Mycoplasmas-Mycoplasma Pnuemoniae
2. Chlamydia- Chlamydia trachomatis
22
Q
Name a bacteria that has a cell wall but does not stain well with Gram stains
A
Mycobacteria
23
Q
List 3 structures present in Gram positive bacteria
A
- Thick peptidoglycan cell wall
- Teichoic acid
- Lipoteichoic acid
24
Q
List 5 structures present in a Gram negative bacteria
A
- Lipopolysaccharide (on the outer membrane)
- Porin
- O specific chains
- Thin peptidoglycan wall (between the membranes)
- Integral proteins (between the bilayer)
25
What is the main job of lipopolysaccharide
Endotoxin
| Endo means 'part of'
26
List 3 features of a Peptidoglycan cell wall
1. N-acetylated sugars
- glucosamine(NAG) and muramic acid (NAM)
2. 3-5 amino acid peptides
3. Transpeptidase enzymes (involved in cell wall synthesis)
27
list 3 steps involved in the synthesis of peptidoglycan
1. Polymerisation of sugar (NAM and NAG)
2. Elongation of aa (add peptides)
3. Cross link transpeptidase
28
Why cant Mycobacteria be stained and what other feature enables its survival
Its peptidoglycan is protected by an outer membrane called Myco-membrane/mycolic membrane. Prevents crystal violet from going into the bacteria. It also allows mycobacteria to be anti-phagocytic.
29
List 2 disease caused by Mycobacteria
1. Tuberculosis
| 2. Leprosy
30
List 6 important features of bacteria
1. Capsule
2. Spores
3. Ribosomes
4. Peptidoglycan cell wall
5. Lipopolysaccharides (in Gram negatives)
6. Mobile genetic elements (Plasmids and transposons-move location in genome)
31
Plasmids and transposons are mobile genetic elements that codes for toxins and antibiotic resistance genes. True or False
True
32
Endo spores in some bacteria enables it to develop resistance to...
List 4 processes
1. Drying
2. Temperature
3. Disinfection
4. Digestion
33
List the 4 stages in bacterial growth
1. The lag phase (bacteria adapting to new environment)
2. The Exponential phase
3. The Stationary phase (nutrients in cells become depleted, division stops)
4. Death phase (exhaustion of resources)
34
List the 5/6 main mechanisms of viral pathogenesis
```
1. Implantation at site of entry (normally sterile sites)
Survive after entry
2. Local replication
3. Spread to target organs
4. Multiplication at target organ
5. Shedding of virus into atmosphere
```
35
Describe types of viral infections
1. Acute infection
| 2. Chronic infection (Continuous replication + latency)
36
What is Latency
Persistence of Viral DNA after infection. Can either be extrachromosomal element (herpesviruses) or integrated within the host genome (retroviruses) and is also replicated when cell replicates.
Reactivation(HV) as blisters, cold sores or shingles from chicken pox/Transformation(RS) of cell leading to cancer
37
Explain methods of acquiring viral infection
1. Endogenous - Latency Reactivation
| 2. Exogenous
38
What is Virulence
Virulence is how likely an organism is to cause an infection or a disease. It is how likely how organism is a pathogen or a commensal
39
What is Cell tropism
An organism has a predilection(liking) for particular cell types/tissues/organs
40
What is susceptibility
A cell posses a surface molecule that acts as a virus receptor.
Which makes the cell susceptible to the virus
41
What is permissivity
When a cell has appropriate transcription factors/enzyme pathways that allows it to switch on viral genes to produce viral proteins.
The cell is permissive to the production of viral proteins
42
List different methods of viral diagnosis
1. Microscopy
2. Culture
3. Detection of antibody mounted against the virus
4. Detection of viral protein
5. Detection of viral nuclei acid (Using PCR- Polymerase Chain Reaction)
43
Explain concepts of viral prevention and treatment
Prevention - General measures such as masks, gloves + Specific measures such as vaccines
Treatment - Antiviral medicines
44
What is a virion + Nucleocapsid
Virion = Complete virus particle
Nucleocapsid = Nuclei acid + protein coat (like a capsule)
45
What immune system controls Latent viruses
Immuno-surveillance
46
List 2 factors that can increase the likelihood of virus reactivation
1. Aging
| 2. Immunosuppression
47
What is a commensalisation ?
An association between two organisms in which one benefits and the other derives neither benefit or harm.
A commensal is an organism that lives on us but does not cause an infection.
E.g normal microbial flora
48
What is symbiosis
It involves mutual benefit. E.g a mitochondria, takes in nutrients, but produces/releases energy
49
What is a pathogen
An organism which can evade the immune defences of human to cause and infection.
50
What is infection
When an organism gains entry to the body, increase in number and damages its host (invasion, replication and damage)
51
List 3 examples of non-sterile site
Skin,
Mucosal surfaces of upper respiratory tract, alimentary canal
Female genital tract
52
List 3 examples of sterile site
Blood, C.S.F, Bone & joints, muscle, sub-cutaneous tissue, Urine -bladder or renal tract
53
List 2 routes of organisms transmission in the body
1. Through the lymphatics
| 2. Through the blood
54
List 2 reasons why some people get infected and others do not
1. Increased genetic susceptibility, e.g presences of SCD gene in malaria, CFTR gene for C.F (apparently shows resilient to cholera)
2. Inadequate immune response (immunocompromised)
55
Why do some people get sicker than others after an infection
1. Inappropriate or excessive immune response e.g septic shock
56
List 2 ways people can become immunocompromised
1. Primary immunodeficiency syndromes - from birth
| 2. Acquired immunodeficiency- from disease e.g AIDS
57
What is a professional pathogen
A pathogen that almost always causes disease
58
What is an opportunistic pathogen
A pathogen that only causes disease in immunocompromised patient
59
List 3 examples of an opportunistic pathogen
1. Candida albicans
2. staphylococcus epidermidis
3. Staphylococcus aureus
60
List 3 examples of a professional pathogen
1. Neisseria meningitidis
2. Malaria
3. HIV
61
Is staphylococcus aureus a commensal ?
Yes
| Lives in the anterior nares
62
Function of Adhesin molecules in S. aureus virulence
Adhesin molecules -
1. allows it to bind to collagen/elastin on host proteins
2. Immune evasion- as immune system think they are part of the tissue they are bounded to
63
Function of Protein A in S. aureus virulence
Binds to the Fc region of igG antibody. Prevent the Fab region from binding to it.
64
Function of Coagulase in S. aureus virulence
Coagulase on S. aureus stimulates blood clotting. This reduces locomotion of immune cells. Aiding S. aureus in immune evasion.
65
Function of Toxins in S. aureus virulence
Lyse host cells
Exfoliative toxins contain protease that breaks down epidermal structural proteins
Enterotoxins - causes vomiting
66
Function of Capsule in S. aureus virulence
Prevents opsonisation by
1. Preventing FAb region from binding onto the peptidoglycan
2. Even if it does, it prevents Antibody and Complement receptor from binding to their respective antibody/complement.
Hence preventing opsoniosation
67
List 5 features of S. aureus that enables its virulence
1. Adhesins molecule
2. Protein A
3. Coagulase
4. Toxins
5. Capsule
68
Name 2 skin infections caused by S. Aureus
1. Impetigo
| 2. Staph abscess
69
Name a vascular line infection caused by S. aureus
S aureus line sepsis
70
S. aureus causes vomiting as a result of food poisoning with enterotoxins. True or False
True
71
LPS interaction with TLR-4 on macrophage/endothelium causes
Sepsis
1. Inflammatory pathways
2. Coagulation and clotting pathways
3. Change in endothelial integrity
72
TLR 4 recognises LPS
| TLR 2- recognises Lipoteichoic acid/peptidoglycan. True or False
True
73
Non-blanching means
When pressed with glass, the spots remain red
74
List 2 features of Clostridium difficile that aids pathogenicity/virulence
1. Makes toxins that causes diarrhoea
| 2. Production of spores (remember they are rod shaped)
75
Bacteria that can make ATP with or without oxygen are called
Facultative Anaerobe
76
Endotoxin is a feature of the Gram _______ cell wall
Gram Negative cell wall
77
List 2 advantages of Culture-based diagnosis
1. Good for detecting bacteria you can grow/stain
| 2. Reliable identification and resistance testing
78
List 2 disadvantage of culture-based diagnosis
1. Very slow
| 2. Labour intensive
79
Main method used in Microscopy for diagnosis is
Gram staining
80
What is Serology?
Use of serum (blood) to test for immune count. E.g Antibody count
81
Disadvantage of serology
Might need two test. Antibodies can take time to develop (weeks)
82
2 Disadvantage of PCR
Can pick up latent infection in DNA
| Has a poor positive predictive value
83
Advantages of PCR
Good negative predictive value
84
2 Advantages of Whole genome sequencing
1. Rapid
| 2. Cheap
