Ex. 2 - Sterilization and Disinfection

Question 1

It is a process of complete elimination or destruction of all forms of microbial life, both vegetative and spore forms. (spore-forming and nonspore-forming)

Answer 1

Sterilization

Question 2

It is a process of complete elimination of vegetative forms of microorganisms except the bacterial spores from inanimate objects. (vegetative and nonspore-forming)

Answer 2

Disinfection

Question 3

It is the process of removal of pathogenic microorganisms from objects so that they are safe to handle.

Answer 3

Decontamination

Question 4

It is defined as the removal of visible soil (e.g., organic and inorganic materials) from the surfaces and objects.

Answer 4

Cleaning

Question 5

It is the process of removal of germs from the skin.

Answer 5

Antisepsis (disinfection of living tissue or removal of transient microbe from the skin)

Question 6

These are test systems containing viable microorganisms providing a defined resistance to a specific sterilization process.

Answer 6

Biological indicators

Question 7

Commonly used as biological indicators owing to their high resistance to environmental stresses including sterilization process.

Answer 7

Endospores or bacterial spores

Question 8

This is a thermophilic bacteria with an optimum growth temperature range of 55 and 60 degrees Celsius. The spores demonstrate a high resistance toward steam and vaporized hydrogen peroxide.

Answer 8

Geobacillus stearothermophilus

Question 9

This is a mesophilic organism with an optimum growth temperature range of 30 to 39 degrees Celsius. Intended for ethylene oxide, dry heat, and ozone sterilization processes.

Answer 9

Bacillus atrophaeus

Question 10

Physical Sterilization Methods

Answer 10

Heat, Filtration, Ionizing Radiation

Question 11

Under heat, what are the two types and what are they for?

Answer 11

1. Moist heat - coagulates protein

2. Dry heat - kills by oxidation

Question 12

Under moist heat, there are two, what are those?

Answer 12

1. Autoclave

2. Fractional

Question 13

What is fractional heating? What are the two types?

Answer 13

It is the alternate heating (vegetative cells), incubation (spores germinate), and heating (remaining).

> Tyndallization - flowing steam of 100 degrees for 30 minutes for 3 successive days
Inspissation - 75 to 80 degrees Celsius for 2 hours for 3 successive days

Question 14

What are the 3 types under dry heat?

Answer 14

1. Flame
2. Oven
3. Incineration

Question 15

When is flame used?

Answer 15

To sterilize inoculating loops and needles

Question 16

When is oven used?

Answer 16

For glass wares, certain metals, oil, petrolatum, or powders at 160 to 180 degrees Celsius for 1 1/2 to 2 hours with a quality control tester of Bacillus atrophaeus

Question 17

This is the most common method of treating infectious waste that uses 870 to 980 degrees Celsius.

Answer 17

Incineration

Question 18

This is the method of choice for antibiotic solutions, toxic chemicals, radioisotopes, vaccines, and carbohydrates, which are heat-sensitive materials. Also for urea broth and sugar fermentation broth

Answer 18

Filtration

Question 19

T or F: Filtration of liquids can be accomplished by pulling the solution through a cellulose acetate or cellulose nitrate membrane with a vacuum.

Answer 19

True

Question 20

This method makes use of short wavelength but high energy gamma rays for sterilizing plastic syringes, catheter or gloves.

Answer 20

Ionizing radiation

Question 21

This is the most common chemical sterilant that is used in cold sterilization with strict requirements of concentration and humidity. It is also used for materials which cannot be autoclaved. (Quality control: Bacillus atrophaeus)

Answer 21

Ethylene oxide (ETO)

Question 22

Used to sterilize HEPA filters in biological safety cabinets

Answer 22

Formaldehyde vapor and vapor phase hydrogen peroxide

Question 23

Used for cold sterilization and is sporicidal (kills spores) in 3 to 10 hours which is used for medical equipment such as bronchoscopes, because it does not corrode lenses, metal, or rubber.

Answer 23

Glutaraldehyde

Question 24

Cold sterilization that is effective in the presence of organic material, and has been used for the surface sterilization of surgical instruments.

Answer 24

Peracetic acid

Question 25

Physical Disinfection Methods

Answer 25

1. Boiling
2. Pasteurization
3. Non-ionizing radiation

Question 26

100 degrees Celsius for 15 minutes to kill vegetative bacteria

Answer 26

Boiling

Question 27

Used mostly in food industry, eliminates food-borne pathogens and organisms responsible for food spoilage.

Answer 27

Pasteurization

Question 28

Two types of Pasteurization

Answer 28

1. Batch method - 63 degrees for 30 minutes

2. Flash method - 72 degrees for 15 seconds

Question 29

Uses long wavelength, low energy radiation (between 250-300 nm)

Answer 29

Non-ionizing radiation

Question 30

Chemicals used to destroy all life are called ________?

Answer 30

Chemical sterilants or biocides

Question 31

Disinfectants used on living tissue (skin) are called ______?

Answer 31

Antiseptics

Question 32

Destroys vegetative forms on inanimate objects (microbicidal). Examples include phenol, phenolics, QUATS, chlorine, 2% aq. glutaraldehyde.

Answer 32

Disinfectants

Question 33

Microbiostatic agents used on living tissues. Examples include alcohol, tincture (alcoholic) iodine, iodophor.

Answer 33

Antiseptic

Question 34

Denatures proteins; make lipids soluble. Use is limited to the skin as an antiseptic or on thermometers and injection vial rubber septa as a disinfectant.

Answer 34

Alcohol

Question 35

T or F: 70% ethyl alcohol is more effective as a disinfectant than 95% ethyl alcohol because the increased water hydrolyzing bonds in protein molecules make the killing of microorganisms more effective.

Answer 35

True

Question 36

Disinfectants that kills endospores. Also, toxic to humans.

Answer 36

Aldehydes (in solution) - formaldehyde 8%, glutaraldehyde 2%

Question 37

Halogens

Answer 37

Iodine and chlorine are the frequently used as disinfectant.

Iodine - prepared either as a tincture with alcohol or as an iodophor (iodine + detergent chlorine) coupled to a neutral polymer.

70% ethyl alcohol followed by an iodophor, is the most common compound used for skin disinfection.

Chlorine is most often used in the form of sodium hypochlorite (NaOCl) as household bleach.

Question 38

Heavy metals

Answer 38

Heavy metals containing mercury are no longer recommended since it is toxic.

Eye drop solution containing 1% silver nitrate is still placed in the eyes of newborns to prevent infections with N. gonorrhoeae.

Question 39

Quaternary ammonium compounds (QUATS)

Answer 39

Low toxicity and is used to disinfect bench tops or other surfaces.

Rapidly inactivated by organic matter.

Benzalkonium chloride (Zephiran)

Question 40

Phenolics

Answer 40

Denature proteins; disrupt cell membranes

Disinfectants at high concentrations; used in soaps at low concentrations