Session 1 ILOs - Introduction to infection and microbes Flashcards

1
Q

Definition of infection

A

Infection is the invasion and multiplication of micro-organisms in a host’s tissues that are not normally present (may be symptomatic or asymptomatic)

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2
Q

Explain the 2 types of transmission: Horizontal (diff types) and vertical

A

Horizontal:

  • Contact (direct, indirect or vectors)
  • Inhalation (droplets or aerosols)
  • Ingestion (faecal-oral)

Vertical
- From mother to child (before or during birth)

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3
Q

Explain how we know patients have an infection (including the meaning of the 2 types of investigations)

A
  1. History
    - Symptoms
    - Potential exposure
  2. Examination
    - Organ dysfunctions
  3. Investigations
    - Specific e.g. swabs etc. for bacteriology/virology - tries to identify the causative organism
    - Supportive e.g. CRP, FBCs etc - tells you if the patient has an infection, but can’t give you a name
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4
Q

Name the 4 main categories of micro-organisms (smallest first)

A
  • Viruses
  • Bacteria
  • Fungi
  • Parasites
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5
Q

Name 3 key features of a model virus (from diagram)

A
  • Protein coat
  • Spikes (for attaching to specific cell surfaces)
  • Nucleic acid (genetic code - DNA or RNA)
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6
Q

Name 3 key features of a model bacterium (from diagram)

A
  • Ribosomes (smaller than human ribosomes)
  • Plasmids (smaller circles of DNA - transferable DNA)
  • Capsule and cell wall (polysaccharide molecules - immunogenic)
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7
Q

List the 3 bacterial shapes (2 main ones)

A
  • Coccus (round)
  • Bacillus (rod)
  • Spirillus (very few with clinical importance!)
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8
Q

List the 2 ways coccus bacterial are arranged

A
  • Clusters

- Chains

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9
Q

Outline the differences between gram positive and gram negative bacteria

A

Gram positive:

  • Purple stain is retained = appears purple
  • No outer membrane of lipopolysaccharide
  • Primarily exudes exotoxins
  • Thick outer peptidoglycan layer (multilayered)

Gram negative:

  • Purple stain is NOT retained
  • Lipopolysaccharide outer membrane
  • Primarily exudes endotoxins
  • Only thin peptidoglycan layer (single layered)
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10
Q

Name some virulence factors (promote bacteria) and outline the 2 types of toxins

A

Virulence factors:

  • Host entry (e.g. polysaccharide capsule)
  • Adherence to host cells (e.g. fimbriae)
  • Invasiveness (e.g. enzymes)
  • Iron sequestration (siderophores)

Toxins:

  • Exotoxins
  • Endotoxins
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11
Q

Name the 2 types of fungi - give 2 examples of each

A

Yeasts - single celled

e. g. Candida albicans (thrush)
e. g. Cryptococcus neoformans

Moulds - multicelled

e. g. Aspergillus species
e. g. Dermatophytes (ringworm/athletes foot)

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12
Q

Name the 2 types of parasites - give 2 examples of each

A

Protozoa - single celled

e. g. Giardia lamblia
e. g. Plasmodium falciparum

Helminths - multicelled or worms

e. g. Roundworms
e. g. Tapeworms

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