Session 5

Question 1

What are healthcare infections?

Answer 1

Infections arising as a consequence of providing healthcare
Also includes infections in hospital visitors and healthcare workers, as well as if a patient is infected soon after discharge

Question 2

What are some examples of healthcare infection viruses?

Answer 2

Blood borne e.g hepatitis B, C, HIV
Norovirus e.g winter vomiting disease
Influenza
Chickenpox

Question 3

What are some examples of healthcare infection bacteria?

Answer 3

Staph aureus 
Clostridium difficile 
Escherichia coli 
Pseudomonas aeruginosa
Mycobacterium tuberculosis

Question 4

What are healthcare infection fungi?

Answer 4

Candida albicans

Aspergillosis species

Question 5

When are patients vulnerable?

Answer 5

Elderly/very young
Obese/malnourished
Cancer
Immunosuppressed
Diabetes
Smoker
Surgical patient
Emergency

Question 6

What are some general and specific patient interventions?

Answer 6

General

• optimise patient condition
• antimicrobial prophylaxis
• skin preparation
• hand hygiene

Specific

• MRSA screens
• mupirocin nasal ointment
• disinfectant body wash

Question 7

What are the four ps of healthcare infection prevention?

Answer 7

Patient
- including their interactions with other patients and healthcare workers

Pathogen
- virulence factors and ecological interactions with other bacteria and antibiotics

Practise

• general and specific activities of patients and healthcare workers
• operational implementation of policies
• surveillance
• organisational structure and involvement
• regional and national strategy
• leadership at all levels from government to the ward

Place
- healthcare environment features

Question 8

What are the strategic locations of antigen presenting cells?

Answer 8

Skin - (SALT - skin associated lymphoid tissue)
Mucous membranes - (GALT = gut, NALT = nasal, BALT = bronchus)
Lymphoid organisms - lymph nodes spleen
Blood circulation

Question 9

How to antigen presenting cells capture pathogens?

Answer 9

Phagocytosis (whole microbe)

Macropinocytosis (soluble particles)

Question 10

Where are dendritic cells found and what do they present to?

Answer 10

Found in the lymph nodes, mucous membranes and blood

Present to naive T cells

Question 11

Where are langerhans cells found and where to they present to?

Answer 11

Found in the skin

Present to naive T cells

Question 12

Where are macrophages found and what to they present to?

Answer 12

Found in various tissue

Present to effector T cells

Question 13

Where are B cells found and what do they present to?

Answer 13

found in lymphoid tissue

Present to naive T cells and effector T cells

Question 14

What do extracellular microbes stimulate?

Answer 14

Humoral immunity

Question 15

What do intracellular microbes stimulate?

Answer 15

Cell dependent immunity

• cytoxic t lymphocytes
• antibodies
• macrophages

Question 16

What’s the difference between major histocompatibility complex class 1 and class 2?

Answer 16

Class 1 = found on all nucleated cells

Class 2= found on dendritic cells, macrophages, B cells

Question 17

What are the key features of major histocompatibility complex’s I and II (MHC)?

Answer 17

• Co dominant expression
• polymorphic genes: different alleles amount different individuals
• main functions
  Class 1 = present peptides from intracellular microbes
  Class 2 = present peptides from extracellular microbes

Question 18

What are the respective structures of MHC class 1 and class 2?

Answer 18

• peptide binding cleft: variable region with highly polymorphic residues
• broad specificity
• responsive T cells
  Class 1 recognise CD8+ T cells, endogenous
  Class 2 recognise CD4+ T cells, exogenous

Question 19

How do MHC molecules influence slow progressors and rapid progressors of HIV?

Answer 19

Slow = MHC molecules present key peptides for the survival of the virus (unmutated) = effective T cell response

Rapid = MHC molecules present mutated peptides (less critical for peptides survival) = poor recognition by T cells/poor T cell responses

Question 20

What are the clinical problems with MHC molecules?

Answer 20

Major causes for organ transplant rejection

• HLA molecule mismatch between donor and recipient
• graft versus host reaction

HLA association and autoimmune disease

• ankylosis spondylitis
• insulin dependant diabetes mellitus

Question 21

Give some examples of intracellular and extracellular microbes.

Answer 21

Intracellular

• viruses
• bacteria
• Protozoa

Extracellular

• bacteria
• parasites
• worms
• fungi

Question 22

What medical achievements have been derived from the study of the adaptive immune response?

Answer 22

• disease prevention
• immunoglobulin therapies
• immediate protection
• diagnostic tests

Question 23

What virus causes chickenpox?

Answer 23

Varicella zoster virus

Question 24

What is the immune function of IgG?

Answer 24

Fc dependant phagocytosis
Complement activation
Neonatal immunity
Toxin/virus neutralization

Question 25

What is the immune function of IgA?

Answer 25

Mucosal immunity

Question 26

What’s the immune function of IgM?

Answer 26

Complement activation

Question 27

What’s the immune function of IgE?

Answer 27

Immunity against helminths | Mast cell degranulation

Question 28

What antibody is most prevalent in the primary and secondary response?

Answer 28

``` Primary = IgM Secondary = IgG ```

Question 29

What is the role of cd3?

Answer 29

Co receptors molecules involved in signal transduction

Question 30

How are the right T helper cells activated?

Answer 30

Microbes on macrophage have MHC II/ CD80 or CD86 molecules. MHC II binds with TCR on the Naive TH cell using costimulatory signals (cytokines), leading to the activation of the right t helper cell. (TH1) CD80/86 binds with CD28 with cytokines to activate the right T helper cell. (TH2 and TH17)