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Phase 2a - Introductory Clincal Sciences > Microbiology > Flashcards

Flashcards in Microbiology Deck (184)
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1

Define pathogen.

Organism that causes or is capable of causing a disease.

2

Define commensal.

Organism that colonises the host without causing a disease, in normal circumstances.

3

List 5 locations commensals are found.

1) skin
2) mouth
3) mucosal surfaces
4) urethra
5) vagina

4

List 7 locations commensals are not found, i.e. sterile.

1) blood
2) cerebrospinal fluid
3) pleural cavity
4) peritoneal cavity
5) lower respiratory tract
6) urinary tract
7) joints

5

Define virulence.

The degree to which a pathogen is pathogenic.

6

What is a synonym of virulence?

Pathogenicity.

7

Define virulence factor. (5)

Molecules produced by pathogens that enable them to:
1) colonise host
2) obtain host nutrients
3) immunoevade
4) immunosuppress
5) enter and exit cells (intracellular pathogen)

8

Define asymptomatic carriage.

Pathogen in a tissue site without causing a disease.

9

List Koch’s postulates of disease. (4)

1) microbe must be found in all diseased individuals
2) microbe must be isolated from diseased individual and grown into a pure culture
3) individual inoculated with pure microbe culture should develop disease
4) microbe must be reisolated from inoculated diseased individual

10

Define coccus.

Round bacteria.

11

Define bacillus.

Rod-shaped bacteria.

12

Define diplococcus.

Paired round bacteria.

13

Define vibrio.

Curved rod-shaped bacteria.

14

Define spirochaete.

Spiral rod-shaped bacteria

15

Define spore.

Dormant form of bacteria that is highly resistive to physical and chemical influences.

16

Define opportunistic pathogen.

Organism that causes disease only in immunocompromised individuals.

17

Define desiccation.

A state of extreme dryness.

18

What temperature is the bacterial environment?

-80C to +80C.

19

What pH is the bacterial environment?

pH 4 to pH 9.

20

List 3 forms of mutation that lead to genetic variations in bacteria.

1) substitution
2) deletion
3) insertion

21

List 3 forms of gene transfer that lead to genetic variation in bacteria.

1) transformation, e.g. plasmid
2) transduction, e.g. phage
3) conjugation, e.g. sex pilus

22

How long can spores be desiccated?

>50 years.

23

How long can bacteria be desiccated?

2 hours to 3 months.

24

Define endotoxin.

Lipopolysaccharide (LPS), found on outer membrame of Gram negative bacteria.

25

Define exotoxin.

Proteins secreted by bacteria.

26

Which has a specific action, exotoxin or endotoxin?

Exotoxin.

27

List the 3 components of LPS of Gram negative bacteria.

1) lipid A - toxic
2) core antigen (R) - short sugar chain
3) somatic antigen (O) - repeating oligosaccharide chain

28

Which is stable in high temperatures, exotoxin or endotoxin?

Endotoxin.

29

What is Gram staining?

Staining method used to separate bacteria into two groups, Gram positive and Gram negative.

30

Which doesn’t bind well to immune cell receptors, exotoxin or endotoxin?

Endotoxin.