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Flashcards in Infection Deck (188)
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Define infection

Ann invasion of hosts tissues by microorganisms
Causing disease by microbial multiplication, toxins or host response

1

Give some examples of pathogens using different routes of infection

Self - Escherichia coli - Uti
Direct contact - Herpes Simplex Virus - Cold sore
Vector - Plasmodium vivax - malaria
Faeco-oral (food and water) - Clostridium difficile - c diff
Droplet - Influenza - flu
Aerosol - Mycobacterium tuberculosis - TB
Blood - Hepatitis B - hep B
Vertical transmission - cytomegalovirus (placental), Chlamydia trachomatis (delivery)

2

Differentiate exo and endo toxins

Exo - released by the bacteria usually acting away from the site
Endo - structural components of bacteria

3

Which types of bacteria are more likely to express endotoxins?

Gram -ve

4

What are the toxins released by c diff

type A create pores in enterocytes
type B are cytotoxic

5

What pathogen and host factors influence disease severity?

Pathogen
Virulence of pathogen
Inoculation size
Antimicrobial resistance

Host
Site
Co morbidities
Age

6

What are the two broad categories of investigations for infection?

Supportive (e.g. Cxr, fbc)
Specific (e.g. Micorscopy, culture)

7

What sorts of viruses are effected by alcohol?

Enveloped - disrupts their membrane

8

Examples of Non enveloped viruses (thus less effected by alcohol)

Paravirus 19 (fifths disease)
HPV (warts)
Enteroviruses (polio)
Noroviruses (D/V)
Rotaviruses (D/V)
Hep A and E

9

Give some examples of DNA viruses

Herpes viruses
HBV
Paravirus 19
HPV

10

Counterstain in a gram stain?

Safranin

11

Differentiate the types of fungi

Yeast - single cell (e.g. Candida, pneumocystis jiroveci)
Mould - multi cell (e.g. Aspergillus, tinia)

12

Give 3 examples of protazoa and their disease

Plasmodium - malaria
Giardia lamblia - giardiasis
Trypanosoma cruzi - chagas

13

Cause of bilharzia

Schistosoma mansoni

14

What patient factors influence susceptibility to infection?

Age (Stis in teens and 20s, varied levels of immunity to meningococcal meningitis)
Gender (uti and anatomy, suppressed immunity in males)
Physiological state (preggers, puberty/menopause)
Pathological state (immunocompromised, low blood flow)
Drugs (PPIs, steroids)
Social (living cramped, damp)
Time (seasonal infections, incubation)
Place (current - e.g. Hospital, recent - e.g. Travel infections)

15

What are the two main categories of infection treatment? What can be done in each?

Specific - abx, surgery
Supportive - fluids, o2, pain relief, immunoglobulins, abx against proteins to reduce exotoxin production

16

What are the sirs criteria?

2 OF
Temp >38
Pulse >90
Rr >20
WBC 12x10*9

17

Give some examples of organ dysfunction seen in severe sepsis

Hypotension, confusion, decreased urine output, lactic acidosis

18

Why does sepsis alter coagulation?
What are the consequences

Cytokines initiate thrombin production and inhibit thrombolysis
Endothelial damage exposes TF and impairs prostacyclin production
DIC develops and clots can cause gangrene

19

What are the sepsis 6?

Within one hour:
O2
Bloods for culture
Antibiotics administered
Serum lactate
IV fluids up
Urine output monitored

20

How is meningococcal meningitis subdivided?
What can we vaccinate against

Serogroups a,b, and c
Vaccines for a and c

21

What sort of a response does innate immunity provide to the body?

Fast and non specific

22

What are the first and second line defences of the innate immune system?

First - limits entry and growth
Second - contains and clears

23

What are the four categories of first line innate defences?

Physical - eg epithelial barrier, mucus membrane
Physiological - eg d/v coughing, sneezing
Chemical - eg stomach acid, vaginal acid, molecules (lysozymes, IgA, mucous, pepsin)
Biological - normal flora (compete, actively kill)

24

How does the stomach act as a chemical barrier to infection?

Acid
Pepsin

25

What is involved in second line innate defences?

Phagocytes
Chemicals
Inflammation

26

What do phagocytes use to recognise pathogens?

Use pathogen recognition receptors (PRRs) to detect pathogen associated molecular patterns (PAMPs)

27

Examples of PAMPs with associated bacteria

Lipopolysaccerides (gram -ve)
Peptidoglycan (gram +ve)
Flagellin (flagella bacteria)
Mannose rich glycans (mycobacteria)

28

What can enhance recognition of bacteria by PRRs?

Opsinisation with C3b, C4b, IgG, CRP

29

In which bacteria is opsionisation vital?

Encapsulated bacteria - neisseria meningitidis, streptococcus pneumoniae