Bacteria as causes of diseases Flashcards
1
Q
What is the resolving power of the naked eye
A
100 micrometers
2
Q
What is the resolving power of a light microscope
A
0.2 micrometer
3
Q
Nomenclature of bacteria
A
Genus followed by species name
e.g. Staphylococcus (genus) aureus (species)
4
Q
Define pathogen
A
Organism that causes disease
5
Q
Define commensals
A
Organism which colonises the host but causes no disease in normal circumstances
6
Q
Define Opportunist Pathogen
A
Microbe that only causes disease if host defences are compromised
7
Q
Define Virulence/Pathogenicity
A
The degree to which a given organism is pathogenic
8
Q
Define asymptomatic carriage
A
When a pathogen is carried harmlessly at a tissue site where it causes no disease
9
Q
What does Trypanosoma Gambiense cause
A
Sleeping sickness
10
Q
What do entamoeba histolytic cause
A
Amoebic dysentery
11
Q
What are trypanosomes and entamoeba examples of
A
Eukaryotic cells
12
Q
What does Borrellia recurrent cause
A
recurring fever
13
Q
What does Borrellia Burgdorferi cause
A
Lyme disease
14
Q
What does treponema palladium cause
A
Syphillis
15
Q
What are Borrellia and Treponema palladium
A
Spiral bacteria
16
Q
What does rotavirus cause
A
Vomiting and Diarrhea
17
Q
What areas are open to bacteria
A
ALL mucosal surfaces Skin Beginning of urethra Kidneys Colon Mouth Eyes Anus
18
Q
Are the lungs prone to bacterial colonisation
A
No, they should be sterile
19
Q
What two shapes are most bacteria found in
A
Round (cocci)
Rod-shaped (bacilli)
20
Q
How do gam stains help identify bacteria
A
Divides them into either gram positive or negative bacteria
21
Q
How do we know what bacteria is gram positive
A
Stains purple
22
Q
How do we know what bacteria is gram negative
A
Stains pink
23
Q
What are two cocci gram positive bacteria called
A
diplococcus
24
Q
What is a vibrio
A
Curved rod
25
What is a spirochaete
A spiral rod
26
Examples of spiral rods
Borrellia and Treponema palladium
27
Describe the structure of a bacteria
In order:
1. Inner membrane
2. Outer membrane
3. Cell wall
4. Capsule
- ------
4. Single chromosome of circular double stranded DNA free floating
5. Pilli projecting from outermsmbrane into area (leg-like projections)
28
What bacteria has a double membrane
Gram negative
29
What bacteria has a single membrane
Gram positive
30
role of pilli
Used to attach to the host
31
Role of capsule
Protect from immune system/complement system
Difficult for immune system to recognise bacteria
32
Structure of a gram positive bacteria envelope
1. Single cytoplasmic membrane
2. Layer of peptidoglycan attached to outer part of cytoplasmic membrane
3. Capsule
33
What binds the peptidoglycan layer to the membrane of a gram positive bacteria
Lipoteichoic acid
34
Structure of gram negative envelope
1. Inner membrane
2. THIINNER peptidoglycan sheet
3. Lipoproteins
4. Outer membrane
5. A lipopolysaccharide layer (Endotoxin)
6. Capsule
35
What are the spaces found between the lipoproteins called
Periplasmic space
36
What is the role of the lipopolysaccharide layer
It is a PAMP so can trigger immune response
37
Temperature range for bacteria survival
between -80 and 80 degrees
38
Temperature range for spores
120 degrees
39
pH of bacterial environment
<4
| above 9
40
Define desiccation
Process of extracting moisture
41
Desiccation survival time for bacteria
2hrs - 3months
42
What lightwave can some bacteria survive
UV
43
What bacteria can survive radiation
Radmococcus by surviving on uranium
44
Doubling time for most viruses
1 hour
45
What environment allows microbes to double faster
Broth or media
46
How long does it take to diagnose conditions caused by mycobacterium
6-8 weeks (a LOT longer than other viruses and bacteria)
47
Describe the growth curve of bacteria
1. Lag (slow growth - bacteria getting used to the environment and changing metabolic pathways and producing nutrients)
2. Exponential (rapid increase in colony numbers)
3. Stationary (nutrients run out and competition increases + toxic compounds produced)
48
What is an ENDOTOXIN
Component of the outer membrane of bacteria (lipopolysaccharide)
49
Define an EXOTOXIN
Secreted proteins of gram positive and gram negative bacteria
50
Consequence of an endotoxic shock
Inflammation response
51
Example of an exotoxin
Protein
52
Example of an endotoxin
Lipopolysaccharide
53
Exotoxin vs Endotoxin (specific or non-specific action)
Exotoxin - Specific
Endotoxin - Non-specific
54
How does heat effect exotoxins vs endotoxins
Exotoxins - inactivate
Endotoxins - not effected
55
Extent to how well exotoxins and endotoxins work as an antigen
Exotoxin - strong
| Endotoxin - weak
56
What bacteria produces exotoxins
Gram Positive
| Gram Negative
57
What bacteria produces Endotoxins
Gram Negative (LPS)
58
Can we use an endotoxin as a toxoid
No
59
Can we use an exotoxin as a toxoid
Yes
60
Three ways DNA can mutate
Base substitution
Deletion
Insertion
61
How many base pairs does bacterial chromosome consist of
2-4 x 10^3 Kb
62
Other than bacterial chromosome, where else is DNA found
Bacterial plasmids
63
How many bases are found in plasmid DNA
10-60Kb
64
What are Plasma DNA
Autonomously repeated packets of DNA that are shared between different bacteria (needed for adaptations - e.g. resistance)
65
How are plasmids shared between different types of bacteria
1. Tra locus contains pilin and regulatory genes which form pili
2. Conjugation is initiated by a signal the relaxes enzyme creates nick in one of the strands of the conjugative plasmid.
3. Nicked strand is unwound
4. Strand is replicated
66
Why is a plasmid called an episome
It can integrate itself on bacterial chromosome by homologous recombination
67
Why can some of the host's genes be donated to the recipient
Because plasmids may have replicated genes from host's DNA
68
What three ways are genes spread between bacteria
1. Transformation via plasmids
2. Transduction via Bacteriaphages
3. Conjugation via sex pilus
69
What are bacteriophages and how do they spread DNA between bacteria
1. Viruses that infect bacteria
| 2. Spread DNA as they jump from one bacteria to the next
70
What is an obligate intracellular bacteria
Parasites that can't reproduce outside their host cell
71
Three obligate intracellular bacteria
1. Rickettsia
2. Chlamydia
3. Coxiella
72
How do we distinguish between enterobacteriacae and other forms of bacteria
Add lactose fermenter solution to agar plate (should be able to ferment them)
73
Name three types of enterobacteriacae
1. E. coli
2. Klebsiella
3. Enterobacter
4. Citrobacter
74
What can cause problems when trying to detect lactose-fermenting bacteria
1. Some are late-lactose fermenters
75
How do we detect late-lactose fermenters
Positive ONPG test
76
Two examples of late-lactose fermentors
Serratia
Citrobacter
77
5 examples of lactose non-fermentors
1. Salmonella
2. Shigella
3. Yesrinia
4. Proteus
5. Pseudomonas Aeruginosa
78
Name an anaerobic gram negative bacteria
Bacteroides (B. fragilis)
79
What are coliform
rod-shaped gram-negative non-spore bacteria
80
What are Vibrio bacteria
Gram negative, curved-rod shaped
81
What type of bacteria is Helicobacter
Vibrio
82
What type of bacteria is salmonella
Coliform
83
How can motility help distinguish bacteria
We can see motility patterns showing up on the agar
84
How can we detect if Proteus mirabilis is present on a petri dish
Concentric circles formed by swimming
85
What type of bacteria is Proteus
Coliforms
86
Role of the oxidase test
Tests if micro-organisms contain cytochrome oxidase or indophenol oxidase
87
What is a redox indicator
an indicator which undergoes a definite color change at a specific electrode potential.
88
Give an example of a redox indicator used in the oxidase test
TMPD
89
When oxidised state, what colour is TMPD
Dark blue or maroon
90
What does the oxidised state mean
Organism is able to use oxygen as terminal electron acceptor
