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MSE-2019 Medical Microbiology > Lecture 4 Oxygen and Drugs > Flashcards

Lecture 4 Oxygen and Drugs Flashcards

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1
Q

What does obligate aerobe mean?

A

Oxygen is essential

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2
Q

What is the molecular formula for normal atmospheric oxygen?

A

O2

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3
Q

Why are highly reactive forms of oxygen toxic?

A

They are oxidising (is able to steal electrons from other compounds)

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4
Q

What would happen if I gave oxygen to an obligate anaerobe?

A

It would die lmao

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5
Q

What does an oxidising agent do?

A

Steals electrons from other compounds.
Causes the electron depleted compound to steal electrons from another compound.
So on and so forth
Creating a chain of vigorous oxidation

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6
Q

ToD: Oxidation dmg is reversible

A

False.
Oxidation dmg is irreversible to cells.

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7
Q

What compounds are oxidised causing irreversible dmg?

A

Proteins
Lipids

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8
Q

How many forms of oxygen are there?

A

Four

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9
Q

What does Singlet Oxygen look?

A

O2

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10
Q

What happens to the electrons found within Singlet Oxygen?

A

Aerobic metabolism causes the electrons to be boosted to a higher energy state

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11
Q

What cells use Singlet Oxygen?

A

Phagocytic cells use singlet oxygen to oxidise pathogen

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12
Q

How reactive is Singlet Oxygen?

A

Very reactive oxidising agent

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13
Q

What is the molecular formula for Superoxide Radical?

A

O2-

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14
Q

How are Superoxide Radicals formed?

A

O2- forms during the incomplete reduction of O2 during electron transport in aerobes
&
the metabolism by anaerobes in the presence of oxygen

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15
Q

ToD: Only Anaerobes create Superoxide Radicals

A

False.
Both aerobes and anaerobes can create superoxide radicals

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16
Q

What do aerobic organisms create to detoxify themselves of superoxide radicals?

A

Superoxide dismutase

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17
Q

What do anaerobic organisms create to detoxify themselves of superoxide radicals?

A

Nothing

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18
Q

What is created when you combine two superoxide radicals and two protons?

A

Hydrogen peroxide (H2O2) + Oxygen

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19
Q

What is the molecular formula for Peroxide Anion?

A

O2 2-

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20
Q

What do aerobes have to detoxify themselves of peroxide anion?

A

Catalase or Peroxidase

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21
Q

How are peroxide anions created?

A

They are produced as a biproduct of reactions catalysed by superoxide dismutase

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22
Q

What can you use peroxide anions to make?

A

Hydrogen peroxide

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23
Q

What can hydrogen peroxide be used for?

A

It’s an antimicrobial agent

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24
Q

If there are more metal ions in the body, which form of oxygen is created more?

A

Superoxide radical

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25
Out of the 4 forms of oxygen, which is the most reactive?
Hydroxyl radical
26
What is the molecular form of hydroxyl radical?
OH
27
How are hydroxyl radicals formed?
From ionising radiation and from the incomplete reduction of hydrogen peroxide
28
What enzymes get rid of the hydroxyl radicals?
Catalase and peroxidase
29
ToD: Aerobes produce catalase and peroxidase to get rid of hydroxyl radicals?
True. The build up of hydroxyl radicals can damage proteins, lipids and DNA.
30
What vitamins are considered antioxidants?
Vitamin C Vitamin E
31
What makes vitamins antioxidants?
Able to provide electrons that can reduce the toxic forms of oxygen
32
What are facultative anaerobes?
Can live in various oxygen concentrations
33
What are the two processes that help facultative anaerobes survive?
Fermentation Anaerobic respiration (least efficient due to lack of oxygen)
34
What bacteria is an example of a facultative anaerobe?
E.coli
35
What bacteria is an example of aerotolerant anaerobes?
Lactobacilli
36
What kind of metabolism does aerotolerant anaerobes use?
Anaerobic metabolism
37
At what percentage of atmospheric oxygen are microaerophiles damaged by?
21%
38
What bacteria is an example of an microaerophile?
Helicobacter pylori- ulcer causing pathogen in the stomach
39
What percent of IDU hospital admissions are due to infections?
40%
40
What are the three different types of injection?
Intravenous Intra-muscular Subcutaneous
41
What can cause local abscess formation?
Minor bacterial infections
42
What can cause severe illness if it contaminates injected material or paraphernalia?
Clostridial spores
43
Of IDU hospital admission, what percentage results in death?
20%
44
Where can you find Clostridia?
Widely distributed in soil and gut
45
ToD: Clostridia is gram positive?
True
46
What are the characteristics of Clostridia?
Gram Positive Anaerobic Spore-forming rods Resistant to environmental conditions Can exist as exo-spores May release powerful exotoxins
47
What is required for clostridia spores to germinate?
When introduced to an oxygen-reduced environment
48
What can injecting substances into the muscle tissue do?
Increases the risk of infection via clostridium spores
49
What can be observed on the soft tissue if someone is infected by clostridium spores?
Abscess Cellulitis Fasciitis Myositis
50
What are severe localised symptoms if someone is infected by clostridium spores?
Extensive swelling Pain Oedema Erythema with blackening/blistering at centre Extensive necrosis Necrotising fasciitis
51
Hypothetically if you took drugs and the veins on your arms were too dmged to take more drugs what would you do?
Other areas of the body are free real state e.g Groin area, behind the knees, neck
52
Where can you find C.novyi Type A?
Widely distributed in soil
53
What can be seen on the blood agar if C.novyi Type A is being grown?
After 24H: Small, flat, rough or rhizoidal, translucent haemolytic colonies with a spreading edge After 48-72H: Colonies often coalesce to give fine spreading growth
54
Why shouldn't colonies of C.novyi Type A be exposed to air?
Toxic because the colonies haven't begun sporulation
55
4 Characteristics of C.novyi Type A
Unreactive in commercial anaerobe identification kits (API Anaerobe) Gram-variable Rod shaped Some sub-terminal spores
56
Where can you find C.perfringens?
Post-mortem contaminant Basically dead bodies and necrophiles
57
What are the characteristics of C.perfringens?
Gram-variable Rod shaped No spores
58
What should you see if C.perfringens is growing on blood agar?
24H: Large discrete colonies. Flat and rough-edged or smooth and domed. Non-haemolytic or with a narrow zone of complete haemolysis inside a larger zone of partial haemolysis
59
What are the characteristics of C.septicum?
Grows rapidly Haemolytic Gram variable Rods Numerous sub-terminal spores
60
Where can you most commonly find C.septicum?
Can be found from blood cultures of patients with malignancies of the colon
61
What diseases can C.botulinum cause?
Food-borne illnesses Cases of wound botulism
62
What are the characteristics of C.botulinum?
Haemolysis is variable Gram variable bacilli Profuse sub-terminal and free spores
63
What is observable on the blood agar if C.botulinum is being grown?
Proteolytic types A, B and F will initially produce discrete rhizoidal colonies that spread and coalesce
64
What is observable on the blood agar if C.tetani is being grown?
May produce fine swarming growth
65
What can be seen on the Gram stain of C.tetani?
When left overnight, you will be able see over-decolourised long bacilli without spores
66
What three antibiotics can be given to treat C.histolyticum
Penicillin Metronidazole Clindamycin
67
What is the treatment for patients presenting with compartment syndrome?
Urgent decompression Excision of surrounding oedematous tissues
68
What are the three early surgical interventions for C.histolyticum?
Exploration Drainage Extensive debridement

MSE-2019 Medical Microbiology (6 decks)

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