Session 1 Flashcards

1
Q

How is chickenpox spread?

A

Airborne transmission

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2
Q

Exotoxin vs endotoxin

A

Exotoxins are proteins produced inside the bacterium (usually gram positive) which are secreted into the external environment. E.g. enzymes, AB toxins, diphtheria toxin
Endotoxins are the lipopolysaccharides in the outer membrane of gram negative bacteria. They’re released when the bacterium dies

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3
Q

Information needed from the patient with a potential infection? (Patient history)

A
  • Potential exposures

- Symptoms; duration, severity, local/systemic

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4
Q

EXAMINATIONS for potential infections?

A

Examine for organ dysfunction

- Jaundice > liver dysfunction

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5
Q

INVESTIGATIONS for potential infections?

A

1) Supportive
- CRP
- FBC
- LFT’s
- Kidney function tests (U & E’s)
- Imaging
- Histopathology

2) Specific
- Bacteriology
- Virology

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6
Q

Disease determinants in patient

A

Co-morbidities

Site of infection

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7
Q

Disease determinants for pathogen?

A

Virulence factors
Antibiotic resistance
Inoculum size

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8
Q

Bacteriology?

A
Take specimen and look for bacteria.
- Specimen; tissue, fluids, swabs
- MCS 
microscopy + gram stain culture (bacterial and patient cells)
antibiotic sensitivity
- Rapid antigen test
- Nucleic acid test
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9
Q

Virology?

A
  • Immunohistochemistry for patient antibodies
  • look for viral DNA/ RNA
  • pathogen antigen
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10
Q

What’s a WBC differential?

A
  • percentages of each type of WBC

- included in a full blood count

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11
Q

Reduction in white blood cells?

A

Splenomegaly (stores platelets and WBC’s)
Autoimmune conditions
Liver disease (produce monocytes)
Bone marrow failure

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12
Q

3 categories of WBC?

A

Monocytes- macrophages
Lymphocytes
Granulocytes

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13
Q

Where are the monocytes produced?

A

The reticuloendothelial system /

The mononuclear phagocytic system

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14
Q

Gram stain microscopy

A

Distinguishes between gram positive and gram negative bacteria.

  • Gram positive stain purple because the thick peptidoglycan layer retains crystal violet dye
  • Gram negative stains red due to a thinner peptidoglycan layer
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15
Q

Enriched agar plates

A

Red because it contains blood and proteins which provide nutrients for bacterial growth. Standard plate.

Note; some bacteria are inhibited by blood and won’t grow

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16
Q

Chocolate agar?

Which bacteria grow on chocolate agar?

A

i) Contains lysed blood where the blood cells are lysed so intracellular nutrients are released. It’s darker in colour than enriched agar (red).
ii) haemophilus influenza

17
Q

What is Zika Virus?

A

Virus spread by aedes mosquitoes. Usually a mild infection but very harmful to pregnant women and the foetus (vertical transmission) as it can cause microcephaly (small head).
No vaccine or medication for Zika virus.

18
Q

Examples of healthcare associated infections?

A
  • MRSA, methicilin- resistant staphylococcus aureus.
    Skin infection; DOCTOR, pus, pain
    Deeper; fever, aches, confusion
  • Clostridium difficile
    diarrohea
19
Q

What are Koch’s postulates?

A

4 criteria needed to establish a causative relationship between microbe and disease

20
Q

Anti inflammatory drugs

A
  • corticosteroids (bronchodilation in athsma)
  • NSAID’s (non-steroidal)
    ibuprofen
21
Q

Advantages of the peptidoglycan layer and implications for gram negative bacteria?

A

Determines the shape of the cell
Confers resistance to host peptidases

Bc gram negative bacteria have a thinner peptidoglycan layer. they are more vulnerable to peptidase degradation

22
Q

Structure of the peptidoglycan layer?

A

cross linked polymeric mesh

23
Q

What makes up the outer membrane of gram negative bacteria?

A

embedded LPS, lipopolysaccharide

Lipid = lipid A (TOXIC-  an endotoxin) 
Polysaccharide=  O-polysaccharide (an antigen)
24
Q

Benefits of a capsule for bacteria?

A

Aids pathogenicity:
- Adhere to surfaces
- Diffusion barrier against some antibiotics
- Protection from antibodies- thus phagocytosis
Aids transmission:
- Prevents dessication (drying)

25
Q

What does obligate anaerobe mean?

A

Bacterium which NEEDS anaerobic conditions to survive (it is obligatory).

26
Q

70S ribosome belongs to which type of cell?

A

prokaryotes

eukaryotes have the 80s ribosome

27
Q

Name for single celled/ multicellular fungi?

A
  • Single celled- yeasts
    E.g. candida albicans
  • Multicellular- moulds
    E.g. The Aspergillus species
28
Q

Name for single celled/ multicellular parasites?

A
  • Single celled- protozoa
    E.g Plasmodium falciparum (malaria)
  • Multicellular- helminth (worm)