Controlling Microbial Growth In The Environment

Question 1

Antisepsis

Answer 1

Reduction in the number of microorganisms and viruses, particularly potential pathogens on living tissue

Question 2

Aseptic

Answer 2

Refers to an environment or procedure free of pathogenic contaminants

Question 3

-cide or -cidal

Answer 3

Suffixes indicating destruction of a type of microbe

Question 4

Degerming

Answer 4

Removal of microbes by mechanical means

Question 5

Disinfection

Answer 5

Destruction of most microorganisms and viruses on non-living tissue

Question 6

Pasteurisation

Answer 6

Use of heat to destroy pathogens and reduce the number of spoilage microorganisms in food and beverages

Question 7

Sanitisation

Answer 7

Removal of pathogens from objects to meet public health standards

Question 8

• stasis

- static

Answer 8

Suffixes indicating inhibition but not complete destruction of a type of microbe

Question 9

Sterilisation

Answer 9

Destruction of all microorganisms and viruses in or on an object

Question 10

Action of antimicrobial agents

Answer 10

Alteration of cell walls - when damaged effects of osmosis can cause cell to burst
Cytoplasmic membrane- contents leak out
Non-enveloped viruses can better tolerate harsh conditions
Damage to proteins and nucleic acids -alter or destroy, fatal mutants, halt synthesis

Question 11

Most resistant to least resistant

Answer 11

Prions
Bacterial endospores
Mycobacterium
Cysts of Protozoa
Active stage Protozoa (trophozoites)
Most gram negative bacteria
Fungi
Nonenveloped viruses
Most gram positive bacteria
Enveloped viruses

Question 12

High level germicides

Answer 12

Kill all pathogens including endospores

Question 13

Intermediate-level germicides

Answer 13

Kill fungal spores, protozoan cysts, viruses and pathogenic bacteria

Question 14

Low-level germicides

Answer 14

Kill vegetative bacteria, fungi, Protozoa and some viruses

Question 15

Moist heat

Answer 15

Used to disinfect, sanitise, sterilise and pasteurise
Denatures proteins and destroys cytoplasmic membranes
More effective than dry heat

Boiling
Autoclaving
Pasteurisation
Ultrahigh-temperature sterilisation

Question 16

Desiccation and lyophilisation

Answer 16

Desiccation (drying) inhibits growth due to removal of water
Lyophilisation (freeze-drying) used for long term preservation of microbial cultures - prevents formation of damaging ice crystals

Question 17

Radiation

Answer 17

Particulate radiation - high speed sub atomic particles

Electromagnetic radiation - energy without mass travelling at the speed of light

Question 18

Phenol and phenolic

Answer 18

Denature proteins and disrupt cell membranes
Effective in presence of organic matter
Remain active for prolonged time
Commonly used in health care settings, labs and homes
Have disagreeable odour and possible side effects

Question 19

Alcohols

Answer 19

Intermediate-level disinfectants
Denature proteins and disrupt cytoplasmic membranes
More effective than soap
Swabbing skin with alcohol prior to injection removes most microbes

Question 20

Halogens

Answer 20

Include iodine, chlorine, bromine and fluorine
Intermediate-level antimicrobial chemicals
Damage proteins by denaturation

Question 21

Oxidising agents

Answer 21

Peroxide’s, ozone, and peracetic acid
Kill by oxidation of microbial enzymes
High-level disinfectant
Hydrogen peroxide can disinfect and sterilise wounds because of catalase activity
Ozone treatment of drinking water

Question 22

Surfactants

Answer 22

Surface active chemicals
Reduce surface tension of solvents
Soaps and detergent
Low-level disinfectants

Question 23

Heavy metals

Answer 23

Heavy-metal ions denature proteins
Low-level bacteriostatic and fungistatic agents
Thimerosal used to preserve vaccines
Copper controls algal growth

Question 24

Aldehydes

Answer 24

Compounds containing -CHO groups
Denature proteins and inactivate nucleic acids
Glutaraldheyde disnifects and sterilises
Formalin used in embalming and in disinfection of rooms and instruments

Question 25

Enzymes

Answer 25

Antimicrobial enzymes act against microorganism
Human tears contain lysozyme - digests peptidoglycan wall of bacteria
Lysozyme is used to reduce the number of bacteria in cheese