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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
Q

What is transduction in relation to gene transfer?

A

Bacteriophages mediate transfer of DNA from one bacterium to another

26
Q

What is conjugation in relation to gene transfer?

A

Bacteria having sex through pili; cell-to-cell contact results in DNA transfer

27
Q

What is transposition in relation to gene transfer?

A

Transposons move DNA from one site to another, it can deactivate genes onto which the DNA inserts

28
Q

How do bacteria replicate?

A

Binary fission

29
Q

What is the definition of a pathogen?

A

Organism capable of causing disease

30
Q

What does ‘Koch’s postulates’ mean?

A

He proved that a specific microorganism causes a specific disease

31
Q

What areas of the body should be microbe free?

A 
Blood
CSF
Urine
Muscles
Glands
Brain
Inner Ear
32
Q

What does ‘lethal dose 50’ mean?

A

The dosage that causes 50% mortality in an animal model

33
Q

What are overt pathogens?

A

Pathogens that are only associated with disease; can’t be healthy microbial flora

34
Q

What is an opportunistic pathogen?

A

Normal flora that can cause disease when introduced tp unprotected sites

35
Q

What is a facultative pathogen?

A

A pathogen that can grow and survive in the environment as well as in the host (accidental host)

36
Q

What are sub clinical infections?

A

The presence of bacteria but no pathology (yet)

37
Q

What are examples of bacterial virulence factors?

A 
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
Q

What are the virulence factors of S .pneumoniae?

A 
Capsule prevents phagocytosis
Adhesins attach to respiratory lining.
IgA protease cleaves IgA ans promotes infection spread
Neuroaminifase
Pneumolysins- pore forming
39
Q

What are exotoxins?

A

Proteins released extracellularly

40
Q

What are enterotoxins?

A

Exotoxins that act on the small intestine -> change in intestinal permeability -> diarrhoea

41
Q

What type of bacterium is clostridium botulinum?

A 
Gram+
Anaerobia
Spore forming
Neurotoxin -> botox, resp. arrest
Used to relieve spasticity
42
Q

What type of bacterium is Salmonella enterica?

A

Gram-
Food borne-> gastroenteritis
Hides from immune system in immune cells

43
Q

What type of bacterium is listeria monocytogenes?

A 
Gram+
Rod
Food born -> cheese/ pate
Affects mainly pregnant women/ immunocompromised patients
Can lead to meningitis
Virulence- vacuole escape
44
Q

What are pathogen strategies for immune evasion?

A

Hiding in immune cells
Changing antigens
Decorate outside of cell with molecules similar to the host -> autoimmunity
Blocking/ changing immune response

45
Q

What does ‘dysbiosis’ mean?

A

Imbalance of normal gut microbiota composition

Usually has harmful effects on the host

46
Q

What does ‘probiotics’ mean?

A

Non-pathogenic organisms used as food ingredients to benefit the host’s health
E.g. Yakult

47
Q

What does ‘prebiotics’ mean?

A

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
Q

What is the hygiene hypothesis?

A

Exposure to more dirt strengthens the immune system.

49
Q

How can you change your intestinal microbiome?

A 
Antibiotics
Lifestyle
Diet
Hygiene
Chronic inflammation
Metabolic dysfunction
50
Q

How do commensal species cause infection?

A

Spread into sterile parts of the body

Expand population size numbers

51
Q

How do microbial protectors challenge Koch’s postulate?

A

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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