Host Microbe Interactions Flashcards Preview

RB Y2 CLASP - Sepsis > Host Microbe Interactions > Flashcards

Flashcards in Host Microbe Interactions Deck (35):
1

skin: as a physical barrier 

tightly packed highly keratinised cells

constant renewal and replacement 

2

skin: physiological barriers 

low pH of 5.5 

low oxygen tension 

3

skin: sebaceous glands as barriers 

secrete hydrophobic oils 

lysozyme that destroys the structural integrity of bacterial cell walls

ammonia has anti bacterial properties 

anti-microbial peptides eg defensins secreted by keratinocytes  

4

what are the physical defences in the mucosa of the resp/GI tract 

antimicrobial substances eg lysozyme 

secretory IgA 

gastric acid 

5

what bug do mast cells target 

worms 

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6

how can fungal infections impair the skin barrier 

eg tinea pedis 

cause cracking of teh skin 

7

what cells are phagocytes 

  • neutrophils and macrophages 
  • they are capable of engulfing bacteria and killing via oxygen in/dependent mechanisms 

8

what bug do phagocytes target 

bacteria and fungi 

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9

what are macrophages derived from 

monocytes that have matured in the tissues 

10

which bugs do T lymphocytes protect against 

viruses, fungi and protozoa 

11

helper CD4+ T cells 

activate phagocytes to kill microbes 

  • TH1 activate macrophaes to destroy micro organisms 
  • TH2 activate B cells to rpoduce plasma cells which produce antibodies 

12

13

effector cytokines of Th1 cells 

IF gamma and IL 2

14

effector cytokines of TH2 cells 

IL 4-6 

15

HIV infection 

  • infects CD4+ T cells producing a progressive decline in their numbers 
  • this results in a deficinecy in cell mediated immunity 

16

which disease is there a particularly high risk of in HIV, and how does CD4 count influence this 

  • invasive pneumococcal disease (S. Pneumoniae) 
  • irrespective of CD4
  • eg bacteraemia, meningitidis, empyema etc 

17

when is the pneumonoccal vaccine received: UK VACCINATION SCHEDULE 

  • 2 months 
  • 4 months 
  • withia a year of 1st birthday 
  • 65y 

18

discuss the diseases that one is susceptible to with HIV, influenced by their CD4 count 

  • CD4 <350: TB, candidiasis
  • CD4 <200: Pneumocystic jirovecii, Toxoplasma gondii
  • CD4 <100: CMV

19

name 3 herpesviruses 

CMV, HIV, EBV 

20

what are the classical characteristics of herpesviruses 

cause recurring, latent infections 

21

CMV

  • clinically very similar to glandular fever 
  • causes atypical pneumonia, granulomatous chorioretinitis 

22

which viruses have a risk of feotal damage and congenital infection 

toxoplasmosis and CMV 

23

toxoplasmosis 

  • Protozoan parasite of cats that is transmitted to humans through undercooked meat or contact with cat litter

24

toxoplasmosis infection clinically 

similar to glandular fever

can cause granulomatous chorioretinits, and can be sight threatening if it affects the macula 

25

causes of hyposplenism 

  • splenectomy 
  • functional 
    • sickle cell disease
    • cirrhosis 
    • coeliac 

26

what is one particuarly susceptible to if they have hyposplenism 

invasive infection from encapsulated organisms 

  • Streptococcus pneumoniae (pneumococcus)
  • Haemophilus influenzae type B (HiB)
  • Neisseria meningitidis (meningococcus)

risk can be reduced by vaccination, preferably before splenectomy etc 

27

28

why are elderly people more prone to infection 

  • They are less able to distinguish self from non-self, and so are at a greater risk of autoimmune disease
  • Phagocytes destroy bacteria and antigens more slowly
  • T cells respond more slowly
  • Less antibody is produced, and it binds to antigen less well
  • Less complement is produced

29

what is the aim of immune suppression 

  • create a blunt immune response 
  • reduce damage done due to immune system as a result of autoimmunity
  • to prevent transplant rejection 

30

how does infection present in IC people 

differently 

  • absence of fever
  • lack of inflammatory response 
  • non specific, non localising features 

31

immunosuppression: what can steroids cause in particular 

fungal infections 

32

immunosuppression: anti-TNF alpha therapies 

can reactivate latent TB

fungal infections - particularly Aspergillus 

33

immunosuppression: what can purine analogues cause 

viral infections (HSV and VZV in particular)

pneumocystis jirovecii 

34

what is used as prophylaxis in HIV 

co-trimoxazole 

35

what is used as prophlaxis in a bone marrow transplant 

antifungal agent - itraconazole