Block 2.2 Control of Microbial Growth

Question 1

Infectious Microorganism

Answer 1

Microorganisms capable of causing disease (pathogens)

Question 2

Contaminant

Answer 2

Microbes present @ a given time that are Undesirable or Unwanted

Question 3

Nosocomial (Hospital Aquired) Infection

Answer 3

Infections that develop during a hospital stay

Question 4

Levels of Control of Contamination

Answer 4

1. Normal Household Conditions
2. General Medical Conditions
3. Strict Transmission Control conditions

Question 5

Limit of infections in & Transmission By Health-Care Workers

Answer 5

1. Standard Precautions-assume patients are infectious
2. Biosafety Levels- BSL 1,2,3, &4
3. Special security, storage, & transport of “Select Agents”
4. Sterilization & Disinfecting equipment & skin
5. Use vaccines & antibiotics to augment body defenses

Question 6

Sterile

Answer 6

Free of ALL living microorganisms and spores

Question 7

Sterilization

Answer 7

Using physical procedures or chemical agents to destroy all microbial forms

Question 8

Disinfect/Decontaminate

Answer 8

Use of physical/chemical agents to destroy or inhibit MOST infectious organisms

Question 9

Antisepsis

Answer 9

• Using chemical agents on the skin/living tissues to eliminate or inhibit microorganisms (not necessarily spores)
• Done by applying antiseptic (safe for skin)

Question 10

8 Factors Affecting Effectiveness of Sterilization (No Direct Questions)

Answer 10

1. Microbial Population Composition
   -Resistance to Killing: Endospores > Mycobacterium >
   Protozoan Cysts
2. Microbial Death- not killed instantly
3. Population Size- larger quantity = longer exposure time
4. Concentration/Intensity of Antimicrobial- 70% in some
5. Duration of Exposure
6. Temperature & pH
7. Presence of Protective/Neutralizing Matter- organic matter can protect bacteria
8. Type of material being treated (glass, plastic, liquid, etc)

Question 11

Modes of Action of Microbial Control Methods (No Direct Questions)

Answer 11

1. Damage to cell wall
2. Disrupt Cytoplasmic Membrane
3. Inhibit Synthesis of Proteins & Nucleic Acid
4. Alter Function of proteins & nucleic acids

Question 12

Methods of Physical Control of Microorganisms

Answer 12

1. Cold Temperature
2. Heat
3. Radiation
4. Filtrations

Question 13

Types of Cold Temperature control of Microorganisms

Answer 13

1. Refrigeration- SLOWS metabolism of microbes. NO KILL

2. Freezing- (-70*C)- STOPS Metabolism. NO KILL

Question 14

What is Refrigeration used for?

Answer 14

Prolonging storage & shellfire of food, vaccines, blood, & medications

Question 15

What is Freezing used for?

Answer 15

Long-term storage of microbes & serum

Question 16

How does heat kill cells?

Answer 16

1. Disrupts cell Membrane Functions
   
   • More fluid w/ heat, so loses selective permeability
2. Denatures Proteins
   
   • Heat breaks Hydrogen bonds–> unfolds proteins
3. Inactivates Nucleic Acid
   
   • Heat breaks H Bonds–> Separates DNA strands

Question 17

Is moist heat or dry heat more effective?

Answer 17

• Moist Heat… contains greater “heat energy”

- BUT boiling does not kill endospores

Question 18

Conditions for Dry Heat (hot air oven)

Answer 18

160-180* for 2 Hours

Question 19

Disadvantages of Dry Heat

Answer 19

1. Liquids can’t be heated above boiling point (100*C)

2. Organic compounds can denature @ certain temps

Question 20

What is dry heat used for?

Answer 20

Thermostable, non-liquid (metal or gas)

Question 21

What is Steam Heat

Answer 21

Steam under pressure (autoclave)

Question 22

Conditions of Steam Heat (Autoclave)

Answer 22

121*C for 15 minutes

• Pressure prevents boiling so liquids can be heated
• High Pressure does not cause killing, heat does

Question 23

Limitations of Steam Heat

Answer 23

1. Can’t be used for some Thermolabile substances

2. Can’t be used for items affected b moisture (I.e. surgical instruments w/ sharp cutting edges, dry chemicals, etc)

Question 24

Uses of Steam Heat

Answer 24

1. Sterilize Clean, Wrapped Instruments, containers, & microbial culture media
2. Make contaminated materials safe before discarding

Question 25

Incineration

Answer 25

Burning materials to destroy living cells

Question 26

Uses of Incineration

Answer 26

1. Small, metal, or glass instruments in the lab & on medical wastes

Question 27

Conditions of Incineration

Answer 27

High temp (1800F)... turns waste to ash in seconds

Question 28

Types of Radiation for Sterilization

Answer 28

1. Gamma (Ionizing Radiation) 2. Electron Beam Radiation (Ionizing Radiation) 3. Ultraviolet (Non-Ionizing Radiation)

Question 29

Function of Gamma Radiation

Answer 29

Penetrating deep into objects to Nonspecifically alter cell proteins & nucleic acid

Question 30

Uses of Gamma Radiation

Answer 30

Sterilize pharmaceuticals, medical/dental supplies, & items that can't take steam heat or chemicals (I.e. Gauze)

Question 31

Function of Electron Beam Radiation

Answer 31

Alter Nucleic Acid

Question 32

Uses if Electron Beam Radiation

Answer 32

Decontaminate packages for mail or medical items

Question 33

Function of Ultraviolet Radiation

Answer 33

Mutate nucleic acid to prevent normal gene expression & DNA replication

Question 34

Conditions for UV radiation to have effects

Answer 34

254nm wavelength over 10-30 seconds | -Lowe penetrating power... Direct Contact with microorganism necessary

Question 35

2 Types of Filtration

Answer 35

1. Membrane Micropore Filtration | 2. High-Efficiency Particle Air (HEPA) Filtration

Question 36

Membrane Micropore Filters

Answer 36

Made of: Cellulose Acetate & Nitrate Has pores that trap microbes (0.22 micron sterilizes) Moderately effective on: Viruses, Mycoplasma, chalmydia, & rickettsia

Question 37

Uses for Membrane Micropore Filters

Answer 37

Sterilization of Thermoliable Liquids