Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EMS > Lecture 24: Micro-organisms in Disease: Infection 2 > Flashcards

Lecture 24: Micro-organisms in Disease: Infection 2 Flashcards

1
Q

What is pathogenicity?

A

The capacity of a micro-organism to cause infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 requirements of pathogenicity?

A
  1. Transmissibility
  2. Establishment in or on a host
  3. Harmful side effects
  4. Persistence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is harm often mediated by?

A

Harm is often mediated by host response, rather than by the pathogen itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is Virulence?

A

Virulence sometimes defined as the degree to which a micro-organism is able to cause disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does virulence allow relativity of?

A

Pathogenic potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Infectivity?

A

The ability of a micro-organism to become established on/in a host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What 2 things is infectivity mediated by?

A
  1. Microbial ligand
  2. Host cell surface receptor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is virulence factor?

A

Components of a microorganism which aid its ability to cause infection (infectivity and virulence). Encoded by virulence genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some examples of a virulence factor?

A

Facilitation of adhesion
Toxic effect(s)
Tissue-damage
Interference with host defence mechanisms
Facilitation of invasion
Modulation of the host cytokine responses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 6 stages of the cycle of infection?

A
  1. Encounter
  2. Entry
  3. Spread
  4. Evade defences
  5. Multiply and damage
  6. Disperse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can impact the speed and severity of the cycle of infection?

A

The status of the host system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What two types of sources can infection arise from?

A
  1. Endogenous sources
  2. Exogenous sources
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are endogenous sources?

A

Microorganisms from the host getting into the wrong place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are exogenous sources?

A

Organisms originating from the external environment/infected individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does bacterial pneumonia cause?

A

Infection of the lower respiratory tract– Causes fluid to collect in the alveoli of the lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many people die from pneumonia annually?

A

4 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name 3 organisms that pneumonia can be caused by?

A

Streptococcus pneumoniae
Staphylococcus aureus
Haemophilus influenzae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is gonorrhoea?

A

STI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What organism is gonorrhoea caused by?

A

Neisseria gonorrhoeae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What rank of commonest STI in the UK does gonorrhoea hold?

A

2nd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When is peak incidence of gonorrhoea?

A

Peak incidence 15-19 (women), 20-24 (men)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are 3 symptoms of gonorrhoea?

A

– Discharge of pus from urethra
– Burning sensation
– Sterility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Explain the encounter stage of Bacterial pneumonia?

A
  • Inhalation of air-borne droplets containing pathogen
  • Contact with mouth of infected individual
  • Contaminated blood(?)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain the encounter stage of Gonorrhoea?

A
  • Sexual contact with infected individual
  • Contact with urethral exudate
  • Vertical transmission (mother to child during birth)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is involved in determining tissue tropism of bacterial infection?

A

Adhesins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the complement system?

A

– Part of innate immunity
– Enhance phagocytosis(opsonisation)
– Directly kill cells (membrane attack complex)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is a capsule?

A

Layer of polysaccharide found on the outside of S. pneumoniae and other pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is a capsule’s role for a pathogen?

A

Prevents phagocytosis of pathogen by cells of the immune system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does the capsule help cause pneumonia?

A

Allows S. pneumoniae to passthrough mucus
* Prevents complement-mediated killing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is secretory immunoglobulin A (IgA)

A

Bind to pathogens and prevent them adhering to host tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where is IgA found?

A

Found in mucosal secretions of respiratory tract and urogenital tract

32
Q

What is IgA Protease?

A

An endopeptidase
Degrades IgA

33
Q

How does IgA protease degrade IgA?

A

Targets the amino acid sequence Pro-Pro-Y-Pro (Y=threonine, serine or alanine)
* Hinge region of heavy chain

34
Q

What can IgA be produced by?

A

S. pneumoniae and N. gonorrhoeae

35
Q

What happens to the breakdown of IgA?

A

Breakdown products of IgA stick to the outside of the pathogen

36
Q

What is an incubation period?

A

Period between infection with the organism and manifestation of clinical features

37
Q

What is the incubation period of chicken pox?

A

10-21 days

38
Q

What is the period of infectivity?

A

Period during which a transmissible organism may be transmitted to another person

39
Q

What is the period of infectivity of chicken pox?

A

From 48 hours before the onset of the rash to when all lesions have crusted over

40
Q

What do pathogens require from the host in order to multiply?

A

Nutrients

41
Q

What do pathogen do to the host body? (3)

A
  • Cause direct damage
  • Cause indirect damage
  • Eliciting a strong immune response
42
Q

What is pneumolysin secreted by?

A

Secreted by S. pneumoniae

43
Q

What happens during the multiply stage of the infection cycle?

A

Multiple monomers come together (multimerise) and bind to cholesterol in host plasma membrane
– Pore formation
– Host cell releases internal contents (e.g. nutrients) and dies

44
Q

Which enzyme is capable of degrading Hyaluronic acid and Sialic/neuraminic acid?

A

Hyaluronidase & Neuraminidase

45
Q

What are Hyaluronic acid and Sialic/neuraminic acid components of?

A

Interstitial cement in connective tissue

46
Q

What does the breakdown of Hyaluronic acid and Sialic/neuraminic acid provide?

A

Provide nutrients
– Provide more space for organisms to grow
– Activate immune system

47
Q

What is endotoxin?

A

A component of the outer-membrane in N. gonorrhoeae
– Isn’t actively secreted (it would be called an exotoxin instead!)
– Released on cell death/lysis

48
Q

What impact can endotoxin have on the immune system?

A

Can cause uncontrolled activation of immune response
– Inflammation
– Severe tissue damage
– Multiple organ failure (endotoxic shock, or “sepsis”)

49
Q

What is the host response to severe sepsis/septic shock?

A

– T-lymphocyte response
* Cytokine release: e.g. TNF-α, γ-interferon,interleukin-1
* Fever, rigors, hypotension, tachycardia, collapse
* Cardiac and/or renal failure

50
Q

What does the host response to sepsis activate? (2)

A

– Activation of the clotting cascade (Disseminated intravascular coagulation (DIC) and Depletion of clotting factors)
– Activation of complement

51
Q

What are the 5 stages of impact of infection on the host?

A
  1. Inflammation
  2. Abscess formation
  3. Excessive host response to endotoxin
  4. Toxic effects of exotoxin
  5. Granuloma formation
52
Q

How does the host body defend during inflammation?

A

Activation of complement and clotting systems, fibrinolysis and kinin system
* Leukocyte adhesion and production of inflammatory mediators
* Local vasodilation
* Reduction in endothelial barrier function
* Increased vascular permeability
* Phagocytosis of foreign material

53
Q

How does Erythema arise from inflammation?

A

Vasodilation causes increased blood flow

54
Q

How does swelling arise from inflammation?

A

Increased vascular permeability allows extravasation of serum proteins and leukocytes.
Swelling arises from consequent physical and osmotic effects

55
Q

How does pain arise from inflammation?

A

Caused by a number of different physical and biochemical changes in inflamed tissue1

56
Q

How does heat arise from inflammation?

A

Caused by increased blood flow

57
Q

How does loss of function arise from inflammation?

A

Secondary effect of swelling and pain

58
Q

What is an abscess?

A

An abscess is an enclosed collection of pus
* Consequence of inflammatory response with phagocytosis of organisms

59
Q

What does pus consist of?

A

Pus consists of living and dead white blood cells, exudate, dead tissue and micro-organisms

60
Q

What are 3 clinical features of abscesses?

A

The lesion itself (fluid filled fluctuant mass)
* Surrounding inflammation
* Non-specific symptoms of infection (e.g. anorexia, sweats, malaise, fatigue)

61
Q

What are superficial abscess mainly caused by?

A

Staph. aureus and Strep. pyogenes

62
Q

True or false: Any organism may cause a deep (Intraperitoneal) Abscess?

A

True

63
Q

What is the impact of exotoxin infection on host?

A
  • Proteins produced (& usually secreted) by living bacteria
  • Typically have quite specific effect(s) on host
64
Q

What is tetanus?

A
  • Infection of dirty wounds
  • Toxin production
65
Q

What toxin is produced from tetanus?

A

Tetanospasmin

66
Q

What is tetanospasmin effect on the body?

A

Produced on germination of spores
– Binds to nerve synapses
– Inhibits release of inhibitory neurotransmitters (e.g.gamma-amino butyric acid) in the central nervous system

67
Q

How may tetanus cause death?

A

Can cause respiratory paralysis

68
Q

Give examples of exotoxin-mediated infections?

A

Cholera – Vibrio cholerae
* Diphtheria – Corynebacterium diphtheriae
* Clostridium difficile infection – diarrhoea/colitis
* E. coli O157 haemorrhagic colitis (verotoxin)
* Staphylococcal scalded skin syndrome – Staph. aureus
* Whooping cough (pertussis) – Bordetella pertussis
* Scarlet fever – Strep. pyogenes
* Scalded-skin syndrome – Staph. aureus epidermolysin

69
Q

Give the definition of a granuloma?

A

A focal compact collection of inflammatory cells, mononuclear cells predominating, usually as a result of the persistence of a non-degradable product and of active cell mediated hypersensitivity

70
Q

Give examples of inflammatory stimuli that causes the formation of Granulomas?

A

tuberculosis
other mycobacteria
histoplasmosis
cryptococcosis
toxoplasmosis

71
Q

What type of pathogen is mycobacterium tuberculosis?

A

Intracellular pathogen

72
Q

What accounts for the main clinical and radiological features of TB?

A

Granuloma production

73
Q

What occurs during primary TB?

A

Ranke/Ghon complex: solitary granuloma (nodule) with hilar granulomatous lymphadenopathy

74
Q

What occurs during post-primary/reactivation of TB?

A

Widespread granulomatous inflammation +/- cavitation, often apical

75
Q

What occurs during miliary TB?

A

Multiple disseminated 1-3 mm pulmonary granulomas

76
Q

What occurs during extrapulmonary TB?

A

Diverse manifestations in bone, liver, kidneys, CNS etc

77
Q

What is the infection dose?

A

Number of organisms required to cause infection

EMS (54 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions