Sterilisation and disinfection

Question 1

What is sterilisation

Answer 1

Distructioon of all forms of life including spores

Question 2

Disinfection

Answer 2

Destruction of only pathogenic microorganisms

Question 3

Antisepsis

Answer 3

Distruction of living tissues

Question 4

Order of susceptibility

Answer 4

Prions< bacterial spores < protoazoa cysts< mycobacterium < noneveloped viruses. < Fungi.

Question 5

What are the physical methods of sterilisation and what is the most effective method

Answer 5

Heat most effective

Radiation

Filtration

Question 6

Disinfectantion of mouth of test tubes ,cover slips ,slides

Answer 6

Dry heat flaming

Question 7

Dry heat red heat used in

Answer 7

Sterilisation of inoculating loops, straight wires, tips of foreceps and tip of spatulas

Question 8

What is incineration

Answer 8

Streilization and reduction in the volume of infections hospital waste before disposal

Animal car cases
Human placenta
Soiled bedding and dressings
Cytotoxic drugs

Question 9

How many cambers are there in incinerator

Answer 9

Primary and secondary
Primary 650-750
Secondly 1050 -1100

Question 10

Hot air oven

Answer 10

Sterilisation of metallic instruments 
Glassware, 
powders,
petroleum products 
and sharp instruments,jellies,oils cotton swabs

No rubber products

Question 11

Temperatures of hot air oven

Answer 11

1602 hrs
1701 hrs
180*30 min

Question 12

How can we test the efficacy of hot air oven

Answer 12

Biological method= by spores of bacillus atrophaeus clostridium tetanus

Physical method= temperature chart recorder

Chemical method=brown tube no3

Question 13

What is the mechanism of dry heat

Answer 13

Denaturation of proteins
Oxidative damage
Electrolytic levels of toxic levels

Question 14

Mechanism of moist heat

Answer 14

Denaturation and coagulation of proteins

It is superior to the moist heat

Question 15

Moist heat temperature

Answer 15

Less than 100 * c

Question 16

What is pasteurisation

Answer 16

Disinfection of milk

Holder method= moist heat at 63*c for 30 min

Flash method= moist heat 72 c for 15 to 20 sec
Den decreases to 13 c
It is called rapid cooling

Ultra high heat method 149*c for 0.5 sec

Question 17

Which organism can survive the pasteurisation

Answer 17

Coxiella Burnett’s can survive the holder method

Question 18

Efficacy of pasteurisation

Answer 18

Coliform test

Pasteurised milk+ Macconkey broth

                 Overnight 

If the process success no acid + gas

Question 19

What is the phosphatase test

Answer 19

Pasteurisation + substrate ( disodium phenyl po4)

After 2 hrs

No colour change

Question 20

What is inspissation

Answer 20

Moist 80-85*c fr 30 min for consecutive days

Sterilisation of egg and serum medium
Eg= loefflers medium,Ljmedium

Question 21

What is Tyndallisation

Answer 21

At 100 *c for20 min for 3 consecutive days

Question 22

What do u know about radiation

Answer 22

Radiation is of two types 
Ionising ( uv rays) 
 non ionising ( gamma rays)

Question 23

Ionising radiation eg and mechanism

Answer 23

Uv rays 220-240nm
Mechanism = DNA damage
Poor penetration 
Non sporicidal
Disinfection of safety cabinets, hospital corridors

Question 24

Ionising description

Answer 24

Gamma rays
Mechanism DNA damage
High penetration power 
Sporocidal
Used for disposal 
Gloves
Petriplate
Synringes
IV sets Foley catheters
Sutures implants,prosthesis
Glassware
Fabrics ,contraceptive devices, cotton swabs

Question 25

Efficacy of radiation

Answer 25

Spores of a pumilus

Question 26

Why filtration is used?

Answer 26

For heating sensitive liquids
Eg: antibiotic solutions
Vaccines
Sugar and urea solution

Question 27

What is the pore size

Answer 27

0.45 mue

Question 28

What is the efficacy testing for filtration

Answer 28

Serratia marcescens

Brevundimonas diminutive

Question 29

Types of filtrations

Answer 29

Earthen wave filters

Asbestos filters
Sintered glass filters
Membrane filters

Question 30

Earthen filters

Answer 30

Diaticemous earth and porcelain earth

Candles shape

Question 31

Asbestos earth

Answer 31

Magnesium trisilicate

Shape in form of disks

Question 32

Sintered glass filters

Answer 32

Disk very expensive

Question 33

Membrane filters

Answer 33

Cellulose esters

Disks

Question 34

Efficacy testing of autoclave

Answer 34

Bacillus stearothermophilus