Study Guide Ch. 7 DONE

Question 1

Differentiate between sepsis, asepsis, and antisepsis.

Answer 1

o Sepsis: Refers to bacterial contamination
o Asepsis: Absence of a significant contamination
o Antisepsis: Destroying harmful microorganisms from living tissue

Question 2

Differentiate between physical, chemical, and chemotherapeutic agents of microbial control.

Answer 2

• Physical: Used outside the body
   Involves the use of environmental factors, heat is most common
   Heat is common because
• It accomplishes sterilization
• Can be applied as wet or dry heat
• Denatures proteins
   Filtration
   Radiation
   Temp
   Desiccation and Osmotic Pressure
• Chemical: Used outside the body
   Disinfectants
• Halogens
• Alcohols
• Phenolic Compounds
• Heavy Metals
   Antiseptics
• Chemotherapeutic: Used Internally
   Antibiotics

Question 3

Define disinfection, sterilization and sanitation.

Answer 3

o Disinfection: Destroying harmful microorganisms but does not include spores
o Sterilization: Removing and destroying all microbial life, including spores
o Sanitation: The reduction of vegetative cells to safe numbers

Question 4

Differentiate between holding method of pasteurization, flash pasteurization, and ultra pasteurization.

Answer 4

o Pasteurization: Used to reduce bacterial populations in food or drink,, doesn’t kill spores
o Flash Pasteurization: 71.6C for 15 seconds
o Ultra Pasteurization: 82C for 3 seconds

Question 4

Differentiate between bactericidal and bacteriostatic antimicrobial agents.

Answer 4

o Bactericidal: Kills bacteria
o Bacteriostatic: Inhibiting, not killing bacteria
 Alive just not multiplying because the agent

Question 4

Define thermal death point (TDP) and thermal death time (TDT).

Answer 4

o Thermal Death Point: lowest temp at which all cells in a liquid culture are killed in 10 minutes
o Thermal Death Time: minimal time for all bacteria in a liquid culture ro be killed at a particular temperature

Question 5

Explain why wet heat is better than dry heat accomplishing sterilization.

Answer 5

o Wet heat is better than dry heat because liquids are better conductors of heat then air is.

Question 6

Describe effectiveness, strength, limitations
- Direct flame

Answer 6

o Direct flame:
 Kills by oxidation
 Effectiveness: Complete sterilization when exposed to a flame
 Strengths: Effective for small scale sterilization
 Limitations: Limited to heat resistance materials

Question 7

Define degerming, fungicidal agent, virucidal agent, sporicidal agent, and germicidal agent.

Answer 7

o Degerming: Reduction of viable cells of different types of microorganisms
o Fungicidal agent: Killing fungi
o Virucidal agent: Killing viruses
o Sporicidal agent: Killing spores
o Germicidal agent: Killing germs

Question 8

Describe the different types of preservation methods to delay food spoilage

Answer 8

o Low temp:
- Refrigeration: 4C
- Deep Freezing: -20C
- Lyophilization (freeze drying): very low temp

o Desiccation: Absence of water prevents metabolism

o Osmotic Pressure: high concentration of salts and sugars to create a hypertonic environment (Salting)

Question 9

List and explain the characteristics that a good chemical antimicrobial agent should have and describe the parameters of chemistry that affect the action of a disinfectant.

Answer 9

o Be able to kill or slow the growth of microbes
o Exhibit selective toxicity (kills the microorganisms but doesn’t harm the host)
o Be soluble in water to penetrate well
o Be storable and not separate while standing (To prevent having to stir/mix)
o Work effectively, quickly at low concentration and at the required environmental conditions
o Have no negative impact on the environment
o Not be corrosive (So it won’t damage the surfaces)

Question 10

List the agencies in charge of regulating disinfectants and antiseptics.

Answer 10

FDA and CDC

Question 11

Explain what the phenol coefficient of a disinfectant is, know how to use it to compare the disinfecting efficiency of a given agent and describe the three tests used to determine this coefficient.

Answer 11

o Phenol coefficient (PC) indicates disinfecting agents’ ability compared to that of phenol (slandered of effectiveness for chem agents)
o Know effectiveness because you want it to kill in the lesser concentration
o The Three Tests
 In Use Test:
* Compares the number of vegetative cells on surface before and after disinfection
 Use-Dilution Test:
* Determines the dilution of the chemical that kills bacteria in 10 minutes but not in 5 minutes
 Disc-Diffusion Tests
* Uses filter paper disk soaked in chemicals and placed on a culture

Question 12

Describe effectiveness, strength, limitations
- Hot air oven

Answer 12

o Hot air oven:
 Kills by oxidation at high temps, 160C for 2 hours
 Strengths: Sterilizing glass and metal instruments
 Limitations: Requires long exposure time
 Best use: Items that can withstand heat but are sensitive to moisture

Question 13

Describe effectiveness, strength, limitations
- Boiling

Answer 13

o Boiling:
 100C for 10 minutes, will kill vegetative cells and most viruses but not spores. Boil for two hours to kill spores
 Strength: easy and inexpensive
 Limitations: Doesn’t kill all spores and takes long time

Question 14

Describe effectiveness, strength, limitations
- Autoclave

Answer 14

o Autoclave:
 Uses steam to kill organisms and spores at 121 at 15 psi for 15 minutes

Question 15

Describe effectiveness, strength, limitations
- Tyndallization

Answer 15

o Tyndallization:
 Fractional sterilization, Boiling at 100C for 30 minutes for 3 days consecutive days to kill both vegetative cells and spores
 Effectiveness: Kills both spores and vegetative cells
 Limitations: Time consuming and less reliable then autoclaving
 Strength: Useful for non-autoclavable materials
 Best Use: Freeing spores from media and material that are heat sensitive

Question 16

Describe effectiveness, strength, limitations
- Pasteurization

Answer 16

o Pasteurization:
 Used to reduce bacterial populations in food or drink,, doesn’t kill spores

Question 17

Describe effectiveness, strength, limitations
- Hot oil

Answer 17

o Hot oil:
 160C sterilizes instrument in 1 hour
 Faster then dry heat
 Limited to items that can be submerged

Question 18

Describe effectiveness, strength, limitations
- Filtration

Answer 18

o Filtration:
 Passage of substance through a screen like material
 Ideal for heat sensitive liquds and gases

Question 19

Describe effectiveness, strength, limitations
- Ultraviolet light

Answer 19

o Ultraviolet light:
 Damages microbial DNA by creating Thymine dimers
 Effective at 260nm wavelength
 Good for air and surface disinfecting

Question 20

Describe effectiveness, strength, limitations
- High energy ionizing radiation

Answer 20

o High energy ionizing radiation:
 Creates hydroxyl radicals that damage DNA

Question 21

Describe effectiveness, strength, limitations
-Ultrasound

Answer 21

o Ultrasound: soundwaves to disrupt cells physically
o Good for cleaning before sterilization