Host-microbe interactions

Question 1

What are the barriers to infection in the skin?

Answer 1

Keratinocytes - secrete antimicrobial peptides

Sebaceous glands secrete microbe-inhibiting substances

Antigen-presenting cells in the skin

Question 2

What cell is mainly responsible for control of bacteria and fungi?

Answer 2

Phagocytes

Question 3

What cells activate phagocytes to kill microbes?

Answer 3

Helper T-lymphocytes (CD4+)

Question 4

What do CD8+ T-cells do?

Answer 4

Destroy infected cells containing microbes/microbial proteins

Question 5

What do B cells mature into?

Answer 5

Plasma cells that produce immunoglobulins

Question 6

What antibody is produced first?

Answer 6

IgM

Question 7

What antibody is produced after IgM?

Answer 7

IgG

Question 8

What cells does HIV infect?

Answer 8

CD4+ T-lymphocytes

Causes a decline in these cells

Question 9

What is hyposplenism?

Answer 9

Decreased spleen function

Question 10

Name some ‘functional’ hyposplenism conditions

Answer 10

Sickle cell
Cirrhosis
Coeliac disease

Question 11

Steroids are associated with what type of infection?

Answer 11

Fungal

Question 12

Anti-TNFa therapies are associated with what infections?

Answer 12

Fungal (aspergillus)

Mycobacterium tuberculosis

Question 13

What infections are purine analogues associated with?

Answer 13

Viral (herpes simplex + varicellar zoster)

Pneumocystis jirovecii

Question 14

Give examples of conditions that cause phagocyte deficiencies

Answer 14

Haematological malignancy

Cytotoxic chemotherapy

Question 15

Give examples of conditions that cause T-lymphocyte deficiencies

Answer 15

HIV
Lymphoma
Primary immunodeficiency syndromes (SCID)

Question 16

Give examples of conditions that cause B-cell/antibody impairment or deficiency

Answer 16

Myeloma
Primary immunodeficiency syndromes
Certain immune suppressants (rituximab)

Question 17

What infections are patients with hyposplenism particularly susceptible to?

Answer 17

Streptococcus pneumoniae
Haemophilus influenzae type B
Nesseria meningitidis

Question 18

What prophylaxis is used in patients with HIV?

Answer 18

Co-trmoxazole

Question 19

What prophylaxis is given in bone marrow transplant?

Answer 19

Antifungal agent e.g. itraconazole

Question 20

What does vaccination stimulate the production of?

Answer 20

IgG antibodies

Question 21

What patients receive influenza vaccines?

Answer 21

Pregnant women
Chronic disease
Immunocompromise
Diabetes
Aged >65yrs

Question 22

What patients receive strep pneumoniae vaccinations?

Answer 22

Chronic disease
Hyposplenism
Immunocompromise
Diabetes
Age >65yrs

Question 23

Who receives haemophilus influenzae type B/DTP/MMR vaccines?

Answer 23

All kids

Question 24

What cardiovascular dysfunction is seen in sepsis?

Answer 24

Hypotension due to widespread vasodilatation leading to a fall in peripheral resistance
Corrected with fluid resuscitation +/- inotropes/vasoconstrictors

Question 25

What are some pulmonary dysfunctions in sepsis?

Answer 25

Endothelial injury in lung tissue (capillary leak) Diffuse alveolar oedema Resp failure

Question 26

What renal issues arise in sepsis?

Answer 26

AKI

Question 27

What liver issues arise in sepsis?

Answer 27

Shock liver - transaminitis +/- jaundice due to hypatocyte injury

Question 28

What is transaminitis?

Answer 28

Grossly elevated ALT/AST

Question 29

What causes lactic acidosis in sepsis?

Answer 29

Diffuse hypoperfusion Anaerobic metabolism leads to lactic acid production -> metabolic acidosis Acidosis worsens cardiovascular stability