Infection 1

Question 1

Define infection

Answer 1

Invasion of a hosts tissues by micro-organisms.

Question 2

What are the three ways that micro-organisms cause disease after invading a host?

Answer 2

• multiplication
• toxins
• host response

Question 3

What are some of the main ways infection be gained?

Answer 3

• airborne
• via a vector (e.g Mosquitos)
• from animals
• intimate contact

Question 4

Define Microbiota

Answer 4

A collection of micro-organisms in a particular area that are normally harmless, but if they spread to another area, can cause infection/harm.

Question 5

Give an example of Microbiota.

Answer 5

E.Coli. Has normal presence in the large bowel. If it spreads to the urinary tract, it can cause a UTI.

Question 6

Briefly explain the process of Gram Staining

Answer 6

1. Add crystal violet dye
2. Add iodine- forms a complex with the crystal violet
3. Add acetone
4. Add red dye
   Gram negative bacteria are red, Gram positive remain purple/blue.

Question 7

What is the result of gram staining?

Answer 7

Gram negative bacteria are stained red.

Gram positive bacteria are stained blue/purple.

Question 8

Give two examples of Gram negative bacteria.

Answer 8

E.coli
Shigella
Neissarie
Salmonella

Question 9

Give two examples of Gram positive bacteria.

Answer 9

Staphylococci
Streptococci
Clostridium

Question 10

What is horizontal transmission?

Answer 10

Transmission of infection via contact, inhalation of droplets, aerosols etc.

Question 11

What is vertical transmission?

Answer 11

Transmission of infection from mother to child.

Question 12

Define dissemination.

Answer 12

The act of spreading something.

Question 13

Outline the five steps of micro-organisms causing disease.

Answer 13

Exposure 
Adherence 
Invasion 
Multiplication 
Dissemination

Question 14

Name three disease determinants.

Answer 14

• inoculum size
• resistance
• host co-morbidities
• infection site
• virulence factors (exotoxins and endotoxins)

Question 15

Define exotoxins

Answer 15

Toxin released by bacterium into surroundings

Question 16

Define endotoxins

Answer 16

Toxin in bacterium that are released when it disintegrates.

Question 17

Name some supportive investigations to confirm a diagnosis of infection. (6)

Answer 17

FBC 
LFT
CRP
Kidney function test
Imaging 
History theology

Question 18

Name a specific test used to confirm an infection diagnosis.

Answer 18

Gram staining

Question 19

What does the microbial world consist of? (4)

Answer 19

Viruses, bacteria, fungi and parasites

Question 20

What are bacteriophages?

Answer 20

They are viruses that infect bacteria, which can then go on to cause infection.

Question 21

Describe the appearance of a coccus bacterium.

Answer 21

A round shape

Question 22

Describe the appearance of a bacilli.

Answer 22

A rod shape

Question 23

Describe the appearance of a staphylococcus.

Answer 23

Grapes

Question 24

Describe the appearance of streptococcus.

Answer 24

A strip of cocci.

Question 25

What are obligate aerobes and anaerobes respectively?

Answer 25

Obligate aerobes- requires the prescence of oxygen to survive.
Obligate anaerobes- require the absence of oxygen to survive.

Question 26

Give an example of a yeast fungi.

Answer 26

Candida

Question 27

Give an example of a mold fungi.

Answer 27

Dermatophytes- ringworm and athletes foot.