Introduction to Infection Flashcards

1
Q

What is the definition of symbiosis?

A

Interaction between two different organisms living in close physical association, typically to the advantage of both.

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2
Q

What is a commensal symbiotic relationship?

A

A symbiotic relationship between two different species where one derives some benefit & the other is unaffected.

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3
Q

What is colonisation?

A

When a microbe grows on or in another organism without causing any disease.

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4
Q

List some host risk factors for infection.

A
  1. Extremes of age
  2. Stress & starvation
  3. Compromised barriers - Physical (skin), Biochemical
  4. Immunocompromised host
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5
Q

In which different ways can a host be immunocompromised?

A
  1. Primary immunodeficiency (from birth)
  2. Secondary immunodeficiency (acquired after birth)
  3. Immunosuppression (iatrogenic from immune suppressing treatment).
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6
Q

List 4 physical barriers which prevent most infectious agents from entering the body.

A
  1. Skin
  2. Mucus
  3. Respiratory cilia
  4. Commensal organisms
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7
Q

List 4 biochemical barriers which prevent most infectious agents from entering the body.

A
  1. Sebaceous secretions in skin
  2. Lysozyme in tears
  3. Spermine in sperm
  4. Gastric acid
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8
Q

Which investigations and signs can be used for diagnosing infections?

A
  1. Markers of inflammation in blood or other body fluids
  2. Microscopy, culture & sensitivity testing for bacteria
  3. Nucleic acid detection for viruses
  4. Antibody detection for viruses and unusual pathogens
  5. Antigen detection for unusual pathogens
  6. Imaging studies
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9
Q

What are the 8 steps which bacteria will need to follow to cause infection?

A
  1. Access - can they reach suitable site for adherence?
  2. Adherence - can they stick to suitable site for invasion?
  3. Invasion - can they penetrate the barriers to infection?
  4. Multiplication - can they replicate to cause infection?
  5. Evasion - can they evade the host immune system?
  6. Resistance - can they resist anti-microbial treatments?
  7. Damage - do they damage host cells (directly or indirectly)?
  8. Transmission - can they be released to infect other hosts?
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