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Phase I Medicine > Micro-organisms: Bacteria > Flashcards

Micro-organisms: Bacteria Flashcards

1
Q

What type of E.coli causes food poisoning/ haemolytic uraemia?

A

O157:H7

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2
Q

What family of bacteria does E.coli come from?

A

Enterobacteriaceae

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3
Q

What bacteria is a causative agent of anthrax?

A

Bacillus anthracis

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4
Q

What condition does Neisseria gonorrhoeae cause?

A

Gonorrhoeae

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5
Q

What cellular structures will all bacteria have?

A

Cell wall
Cytoplasm
Ribosomes
Genetic material

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6
Q

How does Helicobacter Pylori deal with the stomach’s acidic environment?

A

Releases urease, converting urea into bicarbonate and ammonia-> cloud of neutralising chemicals protecting it from acid and immune response

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7
Q

What structure determines whether a bacterium is Gr- or Gr+?

A

Cell wall

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8
Q

How does gram staining work?

A

Crystal violet
Wash out with alcohol.
If bacteria is G+, it will retain a purple stain.
Counterstain bacteria with fuchsin.
If the bacteria isn’t Gr+ it will retain a pink stain.

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9
Q

Which type of bacteria has the more complex cell wall structure?

A

Gram negative

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10
Q

How would acid-fast bacteria stain?

A

Gram negative

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11
Q

What staining does mycobacterium tuberculosis require?

A

Ziehl Neelson

Carbolfusion stain

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12
Q

Do Chlamydia and Mycoplasma stain?

A

No

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13
Q

What is M.tuberculosis’ mechanism of action?

A

Inhabit and proliferate within unactivated macrophages in alveoli
Granuloma formation

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14
Q

What endotoxin alerts the host’s immune system of TB?

A

Mycolic acids

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15
Q

Why does Klebsiella pneumoniae take on its stringy texture in culture?

A

The bacterium has a capsule

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16
Q

What bacterium is the causative agent to Lyme disease?

A

Borrelia burgdorferi

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17
Q

What shape is the bacterium Borrelia burgdorferi?

A

Spirochete

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18
Q

What appearance do cocci bacteria have?

A

Chains

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19
Q

Which Gram+ species are spore forming?

A

C. difficile

C. botulinum

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20
Q

What do all bacteria require?

A 
Carbon
Nitrogen
Phosphate
Sulphate
Minerals
Trace elements like iron
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21
Q

How is PCR used with relation to a bacterial genome?

A

Probing for presence of pathogen’s DNA

Probing for presence/absence of antibiotic resistance genes

22
Q

How does diversity of bacteria arise?

A

Mutations
Genetic exchange
Natural selection

23
Q

What are the different forms of horizontal gene transfer?

A

Transformation
Transduction
Conjugation
Transposons

24
Q

What is transformation in relation to gene transfer?

A

Uptake of short DNA fragments by naturally transformable bacteria

25
What is transduction in relation to gene transfer?
Bacteriophages mediate transfer of DNA from one bacterium to another
26
What is conjugation in relation to gene transfer?
Bacteria having sex through pili; cell-to-cell contact results in DNA transfer
27
What is transposition in relation to gene transfer?
Transposons move DNA from one site to another, it can deactivate genes onto which the DNA inserts
28
How do bacteria replicate?
Binary fission
29
What is the definition of a pathogen?
Organism capable of causing disease
30
What does 'Koch's postulates' mean?
He proved that a specific microorganism causes a specific disease
31
What areas of the body should be microbe free?
``` Blood CSF Urine Muscles Glands Brain Inner Ear ```
32
What does 'lethal dose 50' mean?
The dosage that causes 50% mortality in an animal model
33
What are overt pathogens?
Pathogens that are only associated with disease; can't be healthy microbial flora
34
What is an opportunistic pathogen?
Normal flora that can cause disease when introduced tp unprotected sites
35
What is a facultative pathogen?
A pathogen that can grow and survive in the environment as well as in the host (accidental host)
36
What are sub clinical infections?
The presence of bacteria but no pathology (yet)
37
What are examples of bacterial virulence factors?
``` Adhesins Flagella Factors to help obtain nutrients Toxins Capsule Type III secreted molecules (stuff that's secreted directly into the host cell by the bacterium) ```
38
What are the virulence factors of S .pneumoniae?
``` Capsule prevents phagocytosis Adhesins attach to respiratory lining. IgA protease cleaves IgA ans promotes infection spread Neuroaminifase Pneumolysins- pore forming ```
39
What are exotoxins?
Proteins released extracellularly
40
What are enterotoxins?
Exotoxins that act on the small intestine -> change in intestinal permeability -> diarrhoea
41
What type of bacterium is clostridium botulinum?
``` Gram+ Anaerobia Spore forming Neurotoxin -> botox, resp. arrest Used to relieve spasticity ```
42
What type of bacterium is Salmonella enterica?
Gram- Food borne-> gastroenteritis Hides from immune system in immune cells
43
What type of bacterium is listeria monocytogenes?
``` Gram+ Rod Food born -> cheese/ pate Affects mainly pregnant women/ immunocompromised patients Can lead to meningitis Virulence- vacuole escape ```
44
What are pathogen strategies for immune evasion?
Hiding in immune cells Changing antigens Decorate outside of cell with molecules similar to the host -> autoimmunity Blocking/ changing immune response
45
What does 'dysbiosis' mean?
Imbalance of normal gut microbiota composition | Usually has harmful effects on the host
46
What does 'probiotics' mean?
Non-pathogenic organisms used as food ingredients to benefit the host's health E.g. Yakult
47
What does 'prebiotics' mean?
Non-digestible food ingredient that benefits the host by selectively stimulating the growth and/or activity of one/ a limited number of bacteria in the colon -> improving health
48
What is the hygiene hypothesis?
Exposure to more dirt strengthens the immune system.
49
How can you change your intestinal microbiome?
``` Antibiotics Lifestyle Diet Hygiene Chronic inflammation Metabolic dysfunction ```
50
How do commensal species cause infection?
Spread into sterile parts of the body | Expand population size numbers
51
How do microbial protectors challenge Koch's postulate?
An organism is present that can compete against the pathogen Indirectly: Inducting the immune system It's metabolic products Directly: Competing for nutrients Direct toxicity

Phase I Medicine (46 decks)

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