Physical & Chemical methods of Sterilization

Question 1

The process of killing or removing all microbial forms, including spores.

Answer 1

Sterilization

Question 2

The process by which most microbial forms on inanimate objects are killed without necessarily destroying saprophytes and bacterial endospores which leads to a reduction in the number of organisms to a level that they cannot produce infection.

Answer 2

Disinfection

Question 3

Use of chemical agents on living tissue (e.g. skin) to prevent the spread of microorganisms either by inhibiting their growth or destroying them.

Answer 3

Antisepsis

Question 4

Agent, physical or chemical, that kills bacteria.

Answer 4

Bactericidal or Germicidal Agent

Question 5

Agent, physical or chemical, capable of inhibiting the growth of bacteria without necessarily killing them.

Answer 5

Bacteriostatic Agent

Question 6

Agents capable of destroying spores, fungi, and viruses, respectively.

Answer 6

Sporicidal, Fungicidal, Viricidal

Question 7

The most common physical method of sterilization with the use of thermal death time (heat).

Answer 7

Heating

Question 8

Factors That can affect the process of sterilization (heating)

Answer 8

Nature of the heat (Moisture & Dry)
Temperature and Time (Temp Increase, time of sterilization decreases)
Number of Microorganism
Nature of Microorganism
Type of material
Presence of organic material (example: Fats, proteins, and sugars)

Question 9

Types of heat

Answer 9

Moist heat
Vaccine Bath
Serum Bath
Inspissation

Question 10

This method of destroying disease-producing organisms in milk and milk products as well as other beverages.

Answer 10

Pasteurization

Question 11

This method included heating at 72° for 15 seconds followed by a quick rapid cooling at 13°C.

Answer 11

Flash Method

Question 12

This Method is heating at 72°C for 15 seconds and 149°C for 0.5 seconds.

Answer 12

Ultra-High Temperature Method

Question 13

Used to destroy contaminating bacteria in vaccine preparations.

Answer 13

Vaccine Bath

Question 14

In Vaccine Bath, the vaccine preparation is heated in a water bath at 60°C for 1 hour.

Answer 14

True

Question 15

Used to inactivate bacteria contaminating serum preparation and is done by heating at 56°C for several successive days.

Answer 15

Serum Bath

Question 16

Used to solidify and disinfect egg-containing and serum-containing media.

Answer 16

Inspissation

Question 17

In inspissation method, what is the temperature and time after placing the culture medium in the slopes of the inspissator device

Answer 17

80-85°C for 30 minutes

Question 18

This method involves utilizing water at boiling temperature of 100°C. The killing action can be enhanced by the addition of 2% sodium bicarbonate.

Answer 18

Boiling

Question 19

It is also known as “intermittent sterilization “ and involves exposing the material to be sterilized to live steam at 100°C for 30-90 minutes for 3 consecutive days, depending on the material to be sterilized.

Answer 19

Fractional Sterilization

Question 20

The most efficient method of sterilization that destroys all microbial forms.

Answer 20

Autoclave

Question 21

Used to sterilize materials in enclosed tubes, oils, jellies, powders, and glasswares such test tubes and Petri dishes.

Answer 21

Dry Heat

Question 22

Various Methods of Dry Heat includes:

Answer 22

Red Flame
Open Flame
Incineration
Hot Air Oven
Infrared Rays

Question 23

Used to sterilize articles like bacteriological wire loops, straight wires, tips of forceps, and searing spatulas.

Answer 23

Red Flame

Question 24

Used to sterilize such articles as mouths of test tubes, scalpels, glass slides, and cover slips.

Answer 24

Open Flame

Question 25

The purpose is to burn the organism of a contaminated material into ashes (i.e., soiled dressings and beddings, animal carcasses, and pathological materials.

Answer 25

Incineration

Question 26

Used to sterilize certain glasswares (e.g., petri dishes, pipettes, flasks)

Answer 26

Hot Air Oven

Question 27

Used to sterilize metallic equipment and glassware.

Answer 27

Infrared Rays

Question 27

It is used mainly for food preservation, such as in the preparation of dried fish and fruits.

Answer 27

Desiccation

Question 28

It is used for the preservation of microorganisms in a process called lyophilization or freezedrying where the organism is rapidly frozen and then dehydrated in high vacuum and stored in a vacuum-sealed container.

Answer 28

Freezing

Question 29

It is used to remove bacteria from culture media or to prepare suspensions of viruses and phages.

Answer 29

Filtration

Question 30

Ultraviolet Ligh (UVL)/ Non-ionizing Radiation

Answer 30

Used to disinfect hospital wards, operating rooms, laboratories, and other rooms in the hospital that need to be sterilized

Question 31

It exerts its effect by causing formation of free radicals that chemically interact with proteins and nucleic acids, resulting in cell death.

Answer 31

Ionizing Radiation

Question 32

This type of Ionizing Radiation, Used to sterilize syringes, gloves, dressing packs, food, and some pharmaceuticals.

Answer 32

Electron Beams

Question 33

This type of ionizing radiation is Used commercially to sterilize disposable petri dishes, plastic syringes, vitamins, antibiotics, hormones, fabrics, and glassware.

Answer 33

Electromagnetic Rays

Question 34

Exposure to sound waves at a frequency of approximately 20,000 cycles/second for 1 hour can kill some bacteria and viruses. They are used to disinfect and clean instruments and to reduce microbial load

Answer 34

Sonic and ultrasonic vibrations

Question 35

Characteristics that a good chemical agent must possess

Answer 35

Broad spectrum Fast-acting Active in the presence of organic matter Active in any pH level Stable Non-toxic, non-allergenic, non-irritative, and non-corrosive Soluble in water and easy to apply Should leave an residual antimicrobial film on the treated surface Should have high penetrating power Not expensive and easily available Safe under storage & shipping for reasonable periods of time Should not have a bad odor

Question 35

This method is based on the principle of osmosis, so that when the concentration of the fluid surrounding the organism is altered, this will cause the bacterial cell to collapse. This is used for the preservation of fruits in syrup and meats in brine.

Answer 35

Osmotic Pressure

Question 36

Chemical disinfection may be classified based on the following:

Answer 36

Consistency (liquid or gaseous) Spectrum of activity (high level, intermediate level, low level) Mechanism of action

Question 37

Damage to the cell membrane can cause smaller molecules to leak out of the bacterial cell and interfere with the active transport and energy metabolism within the cell.

Answer 37

true

Question 38

They are widely used as disinfectants in homes and hospitals, but their activity is reduced in the presence of hard water and organic matter.

Answer 38

Surface Active Agents

Question 39

Disrupts cell membrane and causes precipitation of proteins and inactivation of enzymes.

Answer 39

Phenolic Compounds

Question 39

Disorganize the lipid structure of the cell membrane, dehydrate cells, and cause denaturation and coagulation of cellular proteins.

Answer 39

Alcohols

Question 40

Denaturing agents are as follows:

Answer 40

Acids and Alkalis Alcohol and Acetone Phenol and cresol

Question 41

Cause damage to the enzyme activity of bacteria.

Answer 41

Heavy Metal

Question 42

Bactericidal oxidizing agents that cause oxidation of essential sulfhydryl groups of enzymes causing inactivation of the enzymes.

Answer 42

Halogens