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Principles of disease JK > Pathogens and host > Flashcards

Flashcards in Pathogens and host Deck (32):
1

Name the 4 things that categorise infection

Inflammation
Pyrexia (fever)
Rigors
Tachycardia

2

Pathogen

An organism which can cause disease

3

Commensal

An organism which is part of normal flora eg Ecoli in gut

4

Koch's postulates
(4 criteria for causative relationship between microorganism and disease)

- Must be found in all cases of disease
- Culture ability outside body
- Reproduce on inoculation
- Microorganism should cause disease when introduced to a healthy individual

5

Pathogenicity ( definition and the 2 categories)

Capacity of an organism to cause disease
Infectivity and virulence

6

Infectivity

Ability to become established eg attachment and acid resistance

7

Virulence

Ability to cause harmful effect once established which are conferred by 3 virulence factors

8

3 virulence factors

Invasive, toxin production and evade immune system

9

Invasiveness

Streptococcus pyogenes
Necrotising fasciitis
Cellulitis
Connective tissue breakdown eg collagenase
Fibrinolysis - streptokinase

10

Endotoxins

Also known as lipopolysaccharide and are part of a gram negative bacterial cell wall

11

Enterotoxins

Exotoxins which act on the GI tract eg vibrio cholera

12

Exotoxins

Toxins released extracellularly by the microorganism eg clostridium tetani

13

Superantigens

Certain exotoxins of staph aureus and strep pyogenes stimulate T cell division
When antigen specific is absent but overwhelming cytokine production ==> Toxic shock

14

Innate immunity

Skin, gastric acid and mucous membranes

15

Phagocytic cells

Macrophages - free in tissues or fixed in organs
Polymorphs which are short lived

16

4 Polymorphs

Neutrophils - Bacteria
Eosinophils - allergen/ parasite
Basophils
Monocyte => Macrophage

17

Are lymphocytes phagocytic?

No

18

Opsonisation

Coated with antibody or complement and phagocytic cell detects both so efficient
Important for capsulate bacteria

19

Monoclonal antibody

Specific for a single epitope

20

Immunoglobulin

Proteins with antibody activity
IgM is primary, IgG is secondary and IgA for mucosal

21

CD4

Helper cells Th1 - cell mediated immunity and activate macrophages - and Th2 - control B cell antibody response

22

CD8

Suppressor and cytoxic cells which kill infected host cell or foreign cells

23

Cell destruction following viral infection

Death of T4+ cells by HIV

24

Virus induced changes to cellular gene expression

Cellular transformation by tumour viruses

25

Immunopathogenic disease

Influenza A virus

26

Overt disease

Visible

27

Antigenic drift

Gradual evolution

28

Antigenic shift

Significant antigenic structure change

29

Acute infection

Influenza A or enterovirus

30

Latent infection

Herpes simplex virus 2 types 1- cold sores 2 - genital lesions

31

Tumour

HPV or retrovirus - lymphoma and leukaemia

32

Asymptomatic

No symptoms - unapparent