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Infection > 2. Infection Model > Flashcards

2. Infection Model Flashcards

1
Q

Outline the basic structure of a virus.

A 
Nucleic acid (DNA or RNA) with a protein capsid coat
Envelope - lipid bilayer
'Spikes' on the outside to aid attachment and entry into host cells.
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2
Q

Give an example of a common virus and its structure.

A

Adenovirus.

DNA, non -enveloped, icosahedral.

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3
Q

What are bacteriophages?

A

Viruses that infect bacteria and are able to transmit DNA between bacteria.

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4
Q

What are the 2 main bacterial shapes?

A

Cocci

Bacilli/rod-like

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5
Q

What is a bacterial capsule commonly made up of?

A

Polysaccharide

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6
Q

How can a bacterial capsule act as a virulence factor?

A

Poor immunogen - evades immune system and protects from phagocytosis.

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7
Q

What colour do gram-positive bacteria stain?

A

Purple

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8
Q

What colour do gram negative bacteria stain?

A

Pink

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9
Q

What is the main structural differences in the cell wall structure of gram positive and gram negative bacteria?

A

Gram positive have a thick outer peptidoglycan layer.

Gram negative have thin peptidoglycan inner layer.
Lipopolysaccharide on the outside.

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10
Q

What is lipopolysaccharide?

A

Virulence factor on the cell wall of gram negative bacteria.

Highly toxic and triggers inflammatory response.

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11
Q

What is an aerobe and an obligate aerobe?

A

Bacteria that can survive in the presence of oxygen.

Obligate aerobes have an absolute requirement for oxygen.

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12
Q

What is an anaerobe and an obligate anaerobe?

A

Anaerobes can survive in the absence of oxygen. Obligate anaerobes must have an oxygen-free environment to survive.

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13
Q

Give an example of an anaerobe.

A

Clostridium difficile

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14
Q

Are spores active or dormant?

A

Dormant form of the bacteria

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15
Q

What is an exotoxin?

A

Toxin that is released from the bacteria to cause host damage.

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16
Q

What is an endotoxin?

A

Toxin that is part of the bacterial structure and is only released during cell breakdown.

17
Q

Give an example of an endotoxin.

A

LPS

18
Q

Give an example of a virulence factor that aids adherence to host cells.

A

Pili

19
Q

Give an example of a yeast fungi.

A

Candida albicans

20
Q

How many cells are yeast fungi made up of?

A

1 (single-celled!)

21
Q

Which 2 pathogens are eukaryotes?

A

Fungi

Parasites

22
Q

Virus’ and bacteria are _________.

A

prokaryotes

23
Q

Give examples of patient factors in the infection model.

A
  • Age
  • Gender
  • Social factors
  • Physiological state
  • Pathological state
24
Q

Why is place an important patient factor?

A

Current - local infections and outbreaks

Recent travel history

25
Q

Why does pathogen interaction with the host defences result in host damage?

A

Causes inflammation.

interaction with cells such as neutrophils releases ROS and cytokines which can trigger local and systemic inflammatory response and host damage.

26
Q

What are the categories of treatment?

A

Supportive

Specific

27
Q

Give examples of commensal bacteria which is found on the skin.

A

Staphylocuccus aureus
Staph. epidermidis
Streptococcus species

28
Q

What infections does adenovirus commonly cause?

A

Conjunctivitis
Respiratory treat infections
Gastroenteritis

29
Q

What method could be used to identify adenovirus?

A

Viral PCR

30
Q

How is adenovirus usually transmitted?

A

Inhaled - easily spread in large groups

31
Q

What is the treatment for adenovirus?

A

Supportive as no anti-virals available.

32
Q

Outline the steps involved in gram-staining.

A
  1. Crystal violet
  2. Rinse, add Iodine
  3. Rinse iodine, decolonize with acetone.
  4. Rinse, apply counterstain safranin
33
Q

Why do gram positive organisms appear purple yet gram negative appear red?

A

Gram positive organisms retain the crystal violet stain due to the thick peptidoglycan layer. Gram negative organisms do not retain this, so take up the red colour of the counterstain safranin.

34
Q

What are the benefits of the microflora in our bodies?

A
  1. Compete with invading pathogens for nutrients and space
  2. Some bacteria in bowel produce antimicrobials
  3. Stimulus for immune development
  4. In gut provide nutrients - Vit K
35
Q

How can microflora become harmful and pathogenic?

A
  1. If they are displaced from their normal site and introduced to a n abnormal site.
  2. Bacteria can convert commonly ingested food into carcinogenic derivatives in colon
  3. Can overgrow in immunocompromised people
36
Q

Outline the structure of bacteria.

A 
DNA - circular
Extra DNA elements - plasmids which are replicable and transferrable 
No membrane-bound organelles
No nucleus 
Cell membrane and wall
Pili and flagella 
Ribosomes
Capsule (sometimes)

Infection (15 decks)

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