Chapter 13

Question 1

Sterilization

Answer 1

Destruction or removal of all viable organisms (surgical equipment)

Question 2

Disinfection

Answer 2

Killing, Inhibition, or Removal of disease causing (pathogenic) organisms
- Disinfectants (usually used on inanimate objects)

Question 3

Sanitation

Answer 3

Reduction of microbial population of lvls deemed safe (dishwasher)

Question 4

Antisepsis

Answer 4

Prevention of infection of living tissue by
microorganisms
- antiseptics
- chemical agents that kill or inhibit
growth of microorganisms when applied
to tissue
- cleaning a wound

Question 5

What is BioSafety Levels determined by?

Answer 5

Determined by:
- Agents Affectivity
- Ease of Transmission
- Potential Disease severity
- Type of work done with the agent

Question 6

What are BSL-1 Agents?

Answer 6

• Dont cause infection in healthy human adults
• include noninfectious disease

Question 7

What are BSL-2 Agents?

Answer 7

• pose moderate risk to laboratory workers and the community, and are typically “indigenous” (commonly found in that geographical area).
• these microbes are there anyway!
• however, cultivating these microbes increase their “biomass” and can pose a problem …Staphylococcus aureus and Salmonella spp., and
  viruses like hepatitis, mumps, and measles
  viruses

Question 8

What are BSL-3 Agents?

Answer 8

• potential to cause lethal infections by inhalation
• either “indigenous” or “exotic,” meaning that they are derived from a foreign location
  Mycobacterium tuberculosis, Bacillus anthracis,
  West Nile virus, and human immunodeficiency
  virus (HIV).

Question 9

What are BSL-4 Agents?

Answer 9

• Most dangerous & Most Fatal.
• Typically exotic and easily transmitted by inhalation, cause infections for which there are no treatments or vaccinations
• only a small number of laboratories in the United States and around the
  world appropriately equipped to work with these agents.Ebola virus and Marburg virus, both of which cause
  hemorrhagic fevers, and smallpox virus

Question 10

Why do we need to control microbial presence and growth and

Answer 10

• essential for treating/curing / preventing infectious diseases,
• controlling food contamination (rotting v.s. fermentation)
• Biotechnological production.

Question 11

What does death depend on?

Answer 11

• Death is not instantaneous
• death rate depends on controlling techniques/agents
• Death rate depends on microbes

Question 12

What is Decimal Reduction Time (DRT / D-Value)?

Answer 12

The amount of time it takes for a specific protocol to produce a one order -of-magnitude decrease in the number of organisms, or the death of 90% of the population.

Question 13

What is Thermal Death Point (TDP)?

Answer 13

The lowest temp of a microorganism at which al microbes are killed in a 10 minute exposure

Question 14

What is Thermal Death Time (TDT)?

Answer 14

The length of time needed to kill all microorganisms in a sample at a given temp.

Question 15

What is incineration and dry oven?

Answer 15

Incineration and dry oven use dry heat and sterilization. Incineration us high destructive and nasty microbes.

Question 16

What physical methods can be used to control microorganisms at Moist Heat?

Answer 16

• Boiling at 100C for various periods of times
• Steam (moist heat and sterilization)
• Autoclave (pressure cooker)

*Note: complete sterilization is not practical form many applications and may alter quality of product. *

Note: Boiling and Autoclave are not ideas ways bc methods may ruin consistency of other organoleptic (sensory) qualities o the food

Question 17

What is Pasteurization?

Answer 17

• Form of microbial control for food that uses heat but does not render the food sterile.
• Kills pathogens and reduces # of spoilages, causing microbes while maintaining food quality.
• pasturized food is NOT STERILE, will eventually spoil

Question 18

What physical methods can be used to control microorganisms at Low temps?

Answer 18

Cooling: (0-7 C)
- Cooling in fridges inhibits microbial metabolism. Certain labs cultures can be preserved by fridges for later use.

Freezing: (-20 C)
- May stop microbial growth, kill susceptible organisms (ice crystal formation). Halted bacterial growth, can restart in thawed foods, should be treated like fresh perishables.

Ultra-Freezing: (< -70C)
- Bacterial cultures and medical specimens requiring long-term storage/transport are often frozen at ultra low temps of -70 or lower). Adding glycerol to sample prevent formation of deadly ice.

Question 19

What physical methods can be used to control microorganisms with Pressure?

Answer 19

works, not convenient.
- Desiccation (removal of moisture): Cells require water for metabolism & survival, drying controls microbial growth but might not kill all microbes, which may start to regrow when conditions are favorable
- “Water activity” can be lower w/o removing the water. Adding solutes to create high osmotic pressures.

Question 20

What physical methods can be used to control microorganisms with Radiation?

Answer 20

Ionizing Radiation: including X-rays, gamma rays, and high energy electron beams. : can easily penetrate paper and plastic, therefore be used to sterilize many packaged materials

Non-ionizing radiation (UV light, 260nm.): does not penetrate packaging.

Question 21

What physical methods can be used to control microorganisms with Filtration?

Answer 21

Air Filtration: High-efficiency particulate air (HEPA) filters, have effective pore size of 0.3 um, small enough to capture bacterial cells, endospores, and many viruses, as air passes through these filters, nearly sterilizing the air on the other side of the filter

Liquid Filtration: Membrane filters to remove microbes from liquid samples. Useful for removing bacteria from various types of heat-sensitive solutions.

Question 22

Chemical: Phenolics

Answer 22

Molecule: Triclosan, Lysol
Mode of Action: Prot. Denaturation Membranes Disruption

Question 23

Chemical: Metals

Answer 23

Molecule: Mercury
Mode of Action: Protein inhibition
Example: Topical

Question 24

Chemical: Halogens

Answer 24

Molecule: Iodine, Chlorine (bleach), Fluorine (Toothpaste)
Mode of Action: React with Cellular Macromolecules
Example: Topical

Question 25

Chemicals: Alcohols

Answer 25

Molecule: Ethanol, Isopropanol
Mode of Action: Prot. denaturation Membranes disruptions
Example: Topical

Question 26

Chemical: Alkylating Agents

Answer 26

Molecule: Formaldehyde
Example: Tissue and specimen storage

Question 27

Chemical: Peroxygens

Answer 27

Molecule: H2O2, Carbamide peroxide
Example: Antiseptic Disinfectant, Acne Medication, Toothpaste Ingredient

Question 28

What is the disk-diffusion method?

Answer 28

The most active compounds produce the larger inhibition zone