Chapter 9: Controlling Microbial Growth In The Environment

Question 1

Disinfection

Answer 1

Destroys vegetative pathogens

Not endospores

Inanimate objects

Question 2

Antiseptic

Answer 2

Applied directly to exposed body surfaces

Disinfectant

Question 3

Sanitization

Answer 3

Cleansing technique

Mechanically removes microbes

Question 4

Degermation

Answer 4

Mechanically removed microbes from skin

Surgical hand scrubbing
Alcohol before venapuncture

Question 5

Bacteriocidal

Answer 5

Kills bacteria

Question 6

Bacteriostatic

Answer 6

Inhibits growth and multiplication of bacteria

Question 7

Cell wall

Answer 7

Integrity of cell

Can’t stop cell from bursting due to osmotic effects

Question 8

Viral envelope

Answer 8

Attachment of virus to target cell

Damage will interrupt viral replication

Question 9

Damage to proteins and nucleic acids

Answer 9

Chemicals
Radiation
Heat
Produces fatal mutants and halts protein synthesis through action on RNA

Depends on shape

Question 10

Most to least susceptible microorganisms

Answer 10

Enveloped viruses
Gram positive
Non enveloped viruses
Fungi
Gram negative
Trophozoites
Cysts of Protozoa 
Mycobacteria
Bacterial endospores

Question 11

High level germicides

Answer 11

Kill all pathogens including endospores

Question 12

Intermediate level germicides

Answer 12

Kill fungal spores protozoan cysts viruses and pathogenic bacteria

Question 13

Low level germicides

Answer 13

Kill vegetative bacteria fungi Protozoa and some viruses

Question 14

Thermal death point

Answer 14

Lowest temp

Kills in broth in 10 min

Question 15

Thermal death time

Answer 15

Time to sterilize volume of liquid at set temp

Question 16

Moist heat

Answer 16

Used to sterilize sanitize and disinfect
Denatures proteins/destroys cytoplasmic membrane
Water is better conductor of heat
Boiling autoclaving pasteurization ultra high temp sterilization

Question 17

Boiling

Answer 17

Kills vegetative cells and most viruses in 10 min

Endospores can survive

Question 18

Autoclaving

Answer 18

Boiling temp⬆️
Pressure⬆️
-121 C

Question 19

Pasteurization

Answer 19

Milk
Not sterilization
Heat tolerant microbes survive 
  •not pathogenic
  •less likely to cause spoilage

Question 20

Batch method pasteurization

Answer 20

30 min at 63 C

Question 21

Flash Pasteurization

Answer 21

15 seconds 72 C

Question 22

Ultra High Temp Pasteurization

Answer 22

1second 140 C
Treated liquids can be kept at room temp
Creamer

Question 23

Dry Heat

Answer 23

Denatures proteins
Oxidizes metabolic and structural chemicals
Higher temp for longer time
Incineration:ultimate mean of sterilization

Question 24

Desiccation

Answer 24

Drying inhibits growth due to removal of water

Microbistatic

Question 25

Lyophilization

Answer 25

Long term preservation of microbial cultures

Question 26

Osmotic pressure

Answer 26

High concentration of salt or sugar in foods inhibit growth Cells in a hypertonic solution of salt or sugar lose water cells dessicates Fungi

Question 27

Radiation

Answer 27

Shorter wavelengths mean more energy and greater penetration Ionizing or non ionizing due to its effects on cellular chemicals

Question 28

Ionizing radiation

Answer 28

Wavelengths shorter than 1 nmelextron brand gamma and x rays Eject electrons from atoms to create ions Ions disrupt hydrogen bonding oxidize double covalent bonds create hydroxide ions which denature other molecules

Question 29

Electron beams

Answer 29

Effective at killing but can't penetrate | Sterilize spices meats micro plastic ware medical and dental supplied

Question 30

Gamma rays

Answer 30

Penetrate well but require hours to kill microbes Sterilize meats spices fruits and veggies

Question 31

X-Rays

Answer 31

Too much time required for practical growth control

Question 32

Non ionizing radiation

Answer 32

Wavelengths > 1 nm Excited electrons and makes them make new covalent bonds Affects 3D structure of proteins and nucleic acid UV light •doesn't penetrate well •thymine dimers in DNA Disinfecting air transparent fluids surfaces of an object

Question 33

Methods of microbial control

Answer 33

Affects microbes cell walls cytoplasmic membranes proteins or DNA Effect varies with temp length of exposure amount of organic matter Varied with pH concentration and age of chemical Effective against enveloped viruses vegetative cells of bacteria fungi Protozoa

Question 34

Phenol

Answer 34

Intermediate to low level disinfectants Denatures proteins and disrupts cell membranes Lysol Remain active for prolonged time

Question 35

Alcohols

Answer 35

Intermediate level disinfectant Denature protein disrupt cytoplasmic membrane Evaporate rapidly Swabbing of skin with 70% ethanol prior injection

Question 36

Halogens

Answer 36

Intermediate anti microbial chemicals Damage enzymes via oxidization Bleach iodine tablets bromine disinfectant

Question 37

Oxidizing agents

Answer 37

Peroxide ozone and peracetic acid kill by oxidization of enzymes High level disinfectants/ antiseptics Hydrogen peroxide disinfects and sterilizes surfaces Ozone treatment for water Sporocide used to sterilize equipment

Question 38

Surfactants

Answer 38

Low level disinfectant Surface active chemicals that reduce surface tension of solvents to make them more effective in dissolving solutes Soaps and detergents Quats: low level colorless and tasteless used for medical and industrial application

Question 39

Heavy metals

Answer 39

Low level bacteriostatic Alter 3D shape of proteins inhibiting or eliminating their function 1% Silver nitrate

Question 40

Aldehydes

Answer 40

Denatures proteins Inactivates nucleic acids Glutaraldehyde disinfects and sterilizes Formalin used in embalming and disinfection

Question 41

Gaseous agents

Answer 41

Denature proteins and DNA by cross linking functional groups Used in hospitals and dental/ vet offices Can be hazardous to people could be explosive and poisonous in high concentration carcinogenic Ethylene oxide

Question 42

Sterilization

Answer 42

Destroys all viable microbes including viruses and endospores Microbicidial