The Control of Microbial Growth

Question 1

Roughly when did the control of microbial growth begin?

Answer 1

Around 100 years ago

Question 2

What were the initial methods of controlling microbial growth around 100 years ago?

Answer 2

Washing hands with chloride of lime

Techniques of aseptic surgery

Question 3

What does sterilisation mean?

Answer 3

The removal or destruction of all microbial life/living microorganisms

Question 4

What is a sterilising agent called?

Answer 4

A sterilant

Question 5

Why is complete sterilisation in commercial sterilisation not often required?

Answer 5

The body’s natural defences can cope

Question 6

What does commercial sterilisation involve?

Answer 6

Heated enough to destroy endospores of clostridium botulinum which can produce a deadly toxin

Question 7

Limited heat treatment in commerce is referred to as

Answer 7

Commercial sterilisation

Question 8

What does disinfection mean?

Answer 8

To remove pathogens - the control is directed at destroying harmful microorganisms

Question 9

What can be used as a disinfectant?

Answer 9

Chemicals, ultraviolet radiation, boiling water or steam

Question 10

What is antisepsis?

Answer 10

When the disinfectant treatment is directed at living tissue it is termed antisepsis

Question 11

What is a chemical that is directed at living tissue called?

Answer 11

An antiseptic

Question 12

What is degerming?

Answer 12

Removing microbes from a limited area - such as when someone is receiving an injection the area is wiped with an alcohol swab

Question 13

What is sanitization?

Answer 13

The lowering of microbial counts on eating utensils

Question 14

What is a biocide/germicide?

Answer 14

Biocides/germicides kill microbes

Question 15

What does the term bacteriostasis mean?

Answer 15

Inhibiting the growth of microbes (not killing)

Question 16

What does sepsis mean?

Answer 16

Refers to microbial contamination

Question 17

What does asepsis mean?

Answer 17

An object/area is free of pathogens / the absence of significant contamination

Question 18

What is the goal os aseptic surgery techniques?

Answer 18

To prevent the microbial contamination of wounds

Question 19

When bacterial populations are heated or treated with antimicrobial chemical, describe how they die.

Answer 19

They usually die at a constant rate. If plotted logarithmically, the death rate is constant as shown with a straight line.

Question 20

If there are 1 million bacteria being treated with an antimicrobial, how many will be left after one minute, two minutes? Say about 90% of the bacteria die each time

Answer 20

One minute, 90% die to 100,000

two minutes, 90% die to 10,000

Question 21

The rate of microbial death depends on four factors. List these.

Answer 21

1. The number of microbes
2. Environmental influences
3. Time of exposure
4. Microbial characteristics

Question 22

How does the number of microbes present affect the rate of microbial death?

Answer 22

The greater the number of microbes there are to begin with, the longer it takes to eliminate the entire population

Question 23

How does the environment play a role in the rate of microbial death?

Answer 23

1. Microbes in biofilms may be difficult to reach

2. Presence of organic matter can inhibit action of chemical antimicrobials

Question 24

Microbial control agents act in three ways. List them.

Answer 24

1. Alteration of membrane permeability
2. Damage to proteins
3. Damage to nucleic acids