The control of microorganism

Question 1

what is autolysis

Answer 1

Cell death linked to activation of lytic enzymes

Question 2

what is the definition of microbial death

Answer 2

The permanent loss of reproductive ability under ideal environmental conditions

Question 3

what is the d value?

Answer 3

decimal reduction time – time required to reduce the viable population by a factor of 10

Question 4

what is a Antimicrobial agent

Answer 4

natural or synthetic chemical that kills or inhibits growth of microorganisms

Question 5

what does Bacteriostatic mean

Answer 5

inhibits bacterial growth

Question 6

what does Bacteriocidal mean

Answer 6

kills cells, but no lysis or cell rupture

Question 7

what does Bacteriolytic mean?

Answer 7

induces killing by lysis releasing cytoplasmic contents

Question 8

Ways that agents kill or inhibit microbes

Answer 8

Alteration of membrane permeability

Damage to nucleic acids

Damage to proteins

Question 9

what does Sterilisation mean

Answer 9

: Destruction of all microbes & viruses from an object. Sterile = absence of all viable organisms

Question 10

what does disinfection mean

Answer 10

Destruction of most microbes & viruses on non-living surfaces (inanimate objects)

Question 11

what does Antisepsis mean

Answer 11

Reduction in number of microbes & viruses (particularly pathogens) on living tissue

Question 12

what does antimicrobial drugs

Answer 12

Destroy microorganisms within the body

Question 13

what does sanitation mean

Answer 13

Removal of pathogens from objects in order to meet public health standards

Question 14

what was some psyhical microbial control methods

Answer 14

Heat (dry or moist)
Radiation (ionising & UV)
Filtration (removal)

Question 15

Physical – heat sterilisation

Answer 15

Macromolecules lose structure & function (denature) at very high temperature

Thermal death time: the time it takes to kill all cells at a given temperature

Thermal death point: the lowest temperature required to kill all cells in 10 min

Question 16

heat sterlisation example

Answer 16

dry heat: incineration, flaming, hot air ovens

Moist heat: boiling or steam under pressure (autoclave). Better penetrating power than dry heat

Pasteurisation: use of heat to reduce the number of disease-producing microorganisms in food & drinks

Unlike the use of chemicals, no toxic residue remains when heat sterilisation is completed

Question 17

what is an autoclave

Answer 17

Moist heat
Sealed chamber
Kills all microbes & endospores

Question 18

what is Pasteurisation

Answer 18

Heat process designed to reduce microbial load in heat sensitive liquids

Question 19

radiation sterlisation?

Answer 19

effective way to sterilise or reduce the microbial burden in almost any substance

Question 20

what are the Two types of electromagnetic radiation

Answer 20

Non-ionising, Ionising

Question 21

what is non ionsing radiation

Answer 21

useful for decontaminating surfaces & materials that do not absorb light (e.g. air & water)

Question 22

what is ionoing radiation

Answer 22

necessary to penetrate & decontaminate solid or light-absorbing materials (effective for sterilising food products & medical supplies)

Question 23

what is the purpose of filter sterllisation

Answer 23

removal of viable cells

Question 24

what is filter sterisation used to sterlise

Answer 24

`thermolabile (heat-sensitive) materials (drugs, vitamins, proteins)
air or gases (e.g. HEPA filters)