sterilization and disinfection

Question 1

removal or destruction of all forms of life, including bacterial spores

Answer 1

Sterilization

Question 2

is the most commonly used method for the removal of microorganisms

Answer 2

Heat

Question 3

It destroys microorganisms by coagulation of enzymes and structural proteins and degradation of nucleic acids

Answer 3

Moist Heat Procedure

Question 4

It destroys vegetative bacteria (non-sporulating)

Answer 4

Boiling

Question 5

Temperature and time of exposure of boiling

Answer 5

100 degree celcius for 10-15 minutes

Question 6

it is a chamber which if filled with hot steam under pressure and is the fastest and simpliest method of sterilization which all organisms (expect prions) and spores are killed within 15 minutes

Answer 6

Autoclave

Question 7

Principle of Autoclave

Answer 7

Steam under pressure

Question 8

Biological indicator of autoclave

Answer 8

Geobacillus stearothermophilus

Question 9

temperature, psi and time for media, liquids, utensils, glass pipettes and instruments for assay

Answer 9

121 degree celsius, 15 psi for 15 minutes

Question 10

temperature, psi and time for decontaminating medical waste

Answer 10

132 degree celsius, 15 psi for 30-60 minutes

Question 11

temperature and time of exposure of fractional/ intermittent sterilization (tyndallization)

Answer 11

100 degree celsius for 30 minutes (3 consecutive days)

Question 12

instrument for tyndallization

Answer 12

Arnold’s sterilizer (free flowing system)

Question 13

it is used to sterilize protein-rich medium such as LJM

Answer 13

Inspissation

Question 14

Principle of Inspissation

Answer 14

Thickening of media through evaporation

Question 15

Temp. and time of exposure of Inspissation

Answer 15

70-80 degree celsius for 2 hours (3 consecutive days)

Question 16

it is used to sterilize milk, dairy products and alcoholic beverages and it eliminates foodborne pathogens and organisms responsible for food spoilage (cannot eliminate bacterial endospores)

Answer 16

Pasteurization/ partial sterilization

Question 17

Treatment at this temperature reduces spoilage of food without affecting its taste
It destroys milk- borne pathogens

Answer 17

Low temperature Holding/ Batch Method

Question 18

Temperature and time of exposure of LTH or batch method

Answer 18

63 degree celsius for 30 minutes

Question 19

temp. and TOE of High temperature short time (HTST) or flash pasteurization

Answer 19

72 degree celsius for 15 seconds (quick heating and immediate cooling)

Question 20

temp. and TOE of UHT

Answer 20

140 degree celsius for 3 seconds (cooled very quickly in a vacuum chamber)

Question 21

Advantage of UHT

Answer 21

milk can be stored at room temperature for 2 months without affecting its flavor; applicable also for coffee creamer

Question 22

it kills microorganism by denaturation of proteins; sterilization without water and it is utilized for the sterilization glassware, oil products and powders

Answer 22

Dry heat procedure

Question 23

Biological indicator of Dry heat procedure

Answer 23

Bacillus subtilis var. niger

Question 24

types of dry heat procedure

Answer 24

flaming (direct heating), oven, incineration, cremation

Question 25

it is used for glassware, oil, petrolatum or powders

Answer 25

oven

Question 26

temperature and TOE of oven

Answer 26

160 to 170 degree celsius for 1.5 to 2 hours

Question 27

is the most common method of treating infectious waste and infected laboratory animal

Answer 27

incineration

Question 28

principle of incineration

Answer 28

burning materials into ashes (300 degrees to 400 degrees)

Question 29

is used to control the spread of communicable diseases

Answer 29

cremation

Question 30

it is the method of choice for sterilization of antibiotic solutions, toxic chemicals, radioisotopes, vaccines and carbohydrates (heat sensitive solutions) and it can also be used for both liquid and air

Answer 30

Filtration

Question 31

2 types of filters

Answer 31

depth filters and membrane filters

Question 32

it consist of fibrous or granular material

Answer 32

Depth filters

Question 33

these are porous membranes (almost 0.1 mm thick) composed of cellulose acetate or polycarbonate

Answer 33

membrane filters

Question 34

types of filtration

Answer 34

liquid filtration, air filtration, filtration of bacteria, yeasts and molds, critical sterilizing

Question 35

it uses cellulose acetate/ cellulose nitrate membrane with a vacuum

Answer 35

liquid filtration

Question 36

it uses hepa filters

Answer 36

Air filtration

Question 37

remove organisms larger than 0.3 micrometer from isolation rooms, operating rooms and biological safety cabinets

Answer 37

Hepa filters

Question 38

it uses 0.45 micrometer pores of membrane filters

Answer 38

filtration of bacteria, yeasts and molds

Question 39

range of membrane filters that removes most bacteria as well a fungi, but not viruses

Answer 39

0.2 to 0.45 micrometer

Question 40

it uses 0.22 micrometer membrane filters for parenteral solutions

Answer 40

critical sterilizing

Question 41

size of membrane filter used to remove vegetative cells but not viruses

Answer 41

0.22 micrometer

Question 42

it is considered bacteriostatic because it reduces the rate of metabolism (0 degree to 7 degree celsius) and is important in microbiology

Answer 42

low/cold temperature

Question 43

destroys bacteria by disruption of metabolism; it involves removing water from microbes (bacteriostatic)

Answer 43

Dessication

Question 44

is the most effective method for long term preservation of microbial cultures and it destroys bacteria by changes in proteins and decreased chemical reactions

Answer 44

lyophilization

Question 45

is the use of high concentrations of salts and sugars in food create a hypertonic environment

Answer 45

osmotic pressure

Question 46

as water leaves the cell, plasma membrane shrinks away from the cell wall (cell may not die, but usually stops growing)

Answer 46

Plasmolysis

Question 47

principle of radiation

Answer 47

when it passes through the cells, it creates free hydrogen and hydroxyl radicals and some peroxidases which in turn cause diff. intracellular damage

Question 48

biological indicator of radiation

Answer 48

bacillus pumilus

Question 49

it causes mutation in DNA and produce peroxides and it destroys vegetative cells and endospores of both prokaryotes and eukaryotes

Answer 49

Ionizaing radiation (cold sterilization)

Question 50

it causes damage to cellular DNA by producing thymine dimmers

Answer 50

non-ionizing radiation

Question 51

long wavelength of

Answer 51

>1nm

Question 52

ultraviolet rays

Answer 52

10-400 nm (260 nm most lethal)

Question 53

it refers to removal, inhibition or killing of microorganisms including potential pathogens by using chemical agents usualy inanimate objects

Answer 53

Disinfection

Question 54

is is applied topically to skin and it inhibits sepsis formation

Answer 54

antiseptic

Question 55

it is usually applied to inanimate objects

Answer 55

Disinfectant

Question 56

it precipitates bacterial protein (h2so4, hcl); it kills all bacteria in the specimen

Answer 56

bactericidal

Question 57

it inhibits the growth of organisms

Answer 57

bacteriostatic