Disinfection

Dr. Shubhangi S. Kshirsagar
Assistant professor
Department of Swasthavritta &Yoga
1
5/3/2021

Definitions
Disinfectant – Usually a chemical agent which
destroys disease causing pathogen or other
harmful microorganism, but might not kill
bacterial spores.
Disinfection –
Thermal or chemical destruction of
pathogen and other type of micro-organism.
Sterilization – free of all forms of viable
organism including bacterial spores.
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5/3/2021 Dr.Shubhangi Kshirsagar

Antiseptic – Substance that prevents or
arrests growth of organism by inhibiting
their activity or by destroying them.
Asepsis - Prevention of contact with
micro-organism
Sterile - State of being free from all living
micro-organisms.
3

Sanitizer – Agent that reduces number
of bacterial contaminants to safe
levels as judged by public health
requirement.
Germicide – Agent that destroys micro-
organism especially pathogenic
organism.
Deodorant – A substance which
suppresses or neutralizes bad odours.
Ex, Lime, bleaching powder
4

Properties of an ideal disinfectant
1. Broad spectrum – wide antimicrobial
spectrum.
2. Economical – no high cost.
3. Easy to use with clear label direction.
4. Solubility – should be soluble in water.
5. Stability – stable in concentrate & use
dilution.
6. Odourless – should have a pleasant odour
7. Not affected by environmental factors.
5

8. Environmentally friendly – should not
damage the environment.
9. Cleaner – good cleaning activities.
10. Residual effect on treated surface leave an
antibacterial film on treated surface.
11. Fast acting – rapid kill.
12. Surface compatibility – should not
corrode instrument & metallic surface.
13. Non toxic – not harmful to the user or
patient.
6

Types of disinfection
1. Concurrent disinfection
2. Terminal disinfection
3. Pre-current (prophylactic)
disinfection
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1. Concurrent disinfection
 Application of disinfective measures as soon
as possible after the discharge of
infectious material from the body of an
infected person, or after the soiling of
articles with such infectious discharges.
 It consists of usually disinfection of urine,
faeces, vomit, contaminated linen, clothes,
hands, dressings, aprons, gloves, etc
throughout the course of an illness.
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2.Terminal disinfection
Application of disinfective measures after
the patient has been removed by death or to
a hospital or has ceased to be a source of
infection or after other hospital isolation
practices have been discontinued.
Terminal disinfection is now scarcely
practised.
Terminal cleaning is considered adequate,
along with long with airing and sunning of
rooms, furniture and bedding.
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3. Precurrent (prophylactic) disinfection
Ex.
Disinfection of water by chlorine
Pasteurization of milk
Hand washing
10

Classification of Disinfective agents
Disinfection
Natural
agent
1. Sunlight
2.Air
Physical
agent
1. Burning
2. Hot air
3. Boiling
4.Autoclave
5. Radiation
Chemical
agent
Solid Liquid Gases
11

Chemical agents
Chemical agents
Solid
1. Lime
2. Bleaching powder
3. Pot Permangate
Liquid
1. Phenol & their
compound
2. Quaternary ammonia
compound
3. Halogen compound
4. Oxidizing agent
5. Heavy metals
6. Alcohol
7. Formalin
Gases
1. Formalin
2. Chlorine
3. Ethyline
oxide
12

Natural agents
13

1. Natural agents
1. Sunlight
 Direct and continuous exposure to sunlight is
destructive to many disease producing
organism.
 UV rays are lethal to bacteria and some
viruses.
 Ex. Linen, beddings, furniture disinfected by
exposure to sunlight for several hours.
 Salmonella typhi destroy within 30min.
 Mycobacterium tuberculi destroy within 3-
4hr.
14

2. Air
 Exposure to open air (airing) acts by drying or
evaporation of moisture, which is lethal to
most bacteria.
15

Physical agents
16

2. Physical Agent
1. Burning/incineration
 Excellent method of disinfection
 Used for disinfection of
Inexpensive articles
 Ex. Dressings, swabs, rags
 Addition of sawdust, paper,
kerosene or other combustible
material aid in burning.
 Faeces can be disposed off by
burning
17

2. Hot air
 Used for disinfection glassware, syringes, swabs,
dressings,oil, sharp instrument.
 Done in hot air oven
Temperature of air in oven should be
maintained at 160-1800 C for at least 1 hour to
kill spore.
Drawback – not suitable for disinfection of
bulky articles (mattresses), because it has no
penetrating power.
18

Hot air oven 19

3. Boiling
Effective method
Boiling for 5-10min will kill bacteria, but not
spores & viruses.
Boiler provide temp well above 900C (for spore
destruction temp needs >1000C
Ex. Linen, rubber goods (gloves), small instrument
which are not used for subcutaneous insertion.
Addition of 1% soap & 0.3% of washing soda to
enhance the effect of boiling.
 Boiling for 30 min is adequate for to disinfect
linen,utensils & bedpan.
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Drawbacks of boiling –
1. Slow process
2. Unsuitable for thick beddings & woolen
material as they shrink and it fixes
albuminous stain.
21

4.Autoclaving
 Autoclave are sterilizers which operate at high
temp( >1000C) & pressure.
They generate steam under pressure (saturated
steam), which is most effective sterilizing agent.
 It works on principle of domestic cooker.
 It attains temp of 1220C under 15
lbs/sq.inch(1kg/sq.cm) pressure
 It acts by giving – latent heat.
22

 Most effective for sterilization of Linen,
dressings, gloves, syringes, certain instruments
and culture media.
 Not suitable for plastics & sharp instruments.
 Categories –
a. Gravity displacement autoclaves
b. High speed prevaccume sterilizer
23

5. Radiation
Ionizing radiation are used for sterilization of
bandages, dressings, catgut & surgical instruments.
The objects to be sterilized are placed in plastic bags
before radiation and they will remain sterile until
opened.
It has great penetrating power with little or no
heating effect.
Most effective method, but very costly
Commercial methods of sterilization are normally
carried out by gamma radiation (atomic).
This technique requires special packing &
equipment.
24

Chemical agents
25

1. Phenol & related compound
1. Pure phenol /
carbolic acid
Not effective
disinfectant
2. Crude phenol (Phenol+Cresol)
 Dark oily liquid
 Effective against gram +ve & -ve
bacteria.
 Slowly effective against spores,
acid fast bacilli & certain viruses.
 5% strength used mopping
floors & cleaning drains.
 Should not used in less than
10% strength for disinfection of
faeces.
 Aqueous solution 0.2 -1% -
bacteriostatic.
26

Phenol & related compound
3. Cresol
Excellent coal tar
disinfectant.
3-10times effective
than phenol.
5-10% soln - faeces &
urine disinfection.
All purpose general
disinfectant.
4. Cresol emulsion
Cresol emulsified
with soap
Lysol, Izal, cylline
Lysol – 50-60%
cresol powerful
disinfectant
2% lysol- feces
disinfection
27

5. Chlorhexidine
(Hibitane)
Skin antiseptic
Highly active against
vegetative gram +ve
organism.
Moderately active
against- gram +ve
microbes.
1% lotion/cream –
burn & hand
disinfection.
6. Hexachlorphane
 Antiseptic
 Highly Active
against gram +ve
organism.
Less active against
gram –ve
organism.
28

7. Dettol (Chloroxylenol)
Non toxic antiseptic and can be used safely
in high concentration.
Active against streptococci.
5% soln used for disinfection of instrument
and plastic equipment. (15 min).
29

2. Quaternary Ammonia compound
1. Cetrimide/Cetavlon
 Bactericidal against
vegetative gram +ve
organism
 Less on –ve organism
 Used in 1-2% strength
 Soluble in water
2. Savlon
(Cetavlon + Hibitane)
1:6 (Savlon: Spirit)- more
effective than 1:20 aq
Soln.
Use -
Plastic appliences
disinfection (normal
strength) within 20min
Thermameter -
3min(1in 6)
Lippes loop 30

3. Halogen & their compound
a. Chlorine & chlorine compound
 Bactericidal
 Fungicidal
 Virucidal
 Tuberculocidal
 Sporicidal
b. Iodine
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a. Chlorine & chlorine compound
1. Bleaching powder/ Chlorinated lime
Formula – CaOCl2
 White amorphous
powder
 Pungent smell of
chlorine
 33% chlorine
Drawback –
Unstable compound.
Loses its chlorine
content on storage.
Action rapid, but brief.
Uses -
Disinfection of feces &
urine in 1hr (5% soln)
Disinfection of well (Water)
Deodorant 32

2. Hypochlorite
 Solid (Ca hypochorite) and
liquid (Na hypochlorite)
 Sodium hypochlorite-
household bleach
 Broad spectrum of
Antimicrobial activity
3. Chlorine tablets/
halozene tablets
Water
disinfection
(small quantity)
33

b. Iodine solution / tinctures
1. Iodine
solution/tincture
 Antiseptic on skin
 Cheap,readily
available,quick action
 Bactericidal
 Fungicidal
 Virucidal
 Lethal to spore
bearing organism
2. Iodophores
Combination of Iodine
& stabilizing agent
Ex. Povidone iodine
(betadine)
Non irritant
Use – blood culture
bottles & medical
equipment disinfection
34

4. Oxidizing agent
1. KMnO4
Purple black crystalline powder
Uses –
 Aquarium disinfection.
 Swimming pool disinfection.
 Fruits & vegetable
disinfection.
2. Hydrogen peroxide -
H2O2
 Bactericidal
 Fungicidal
 Virucidal
 Sporicidal
Uses -
 Hospital – surface disinfection
 3% soln – Antiseptic, Cleaning
wounds
3. Paraacetic acid (H2O2+acetic acid)
Active against gram +ve, fungi, yeast within 5min at<100ppm
In presence of organic matter 200-250ppm is required.
ForViruses – 12-2250ppm 35

5. Alcohol
 Ethyl & isopropyl alcohol –antiseptic & disinfectant.
 Ethyl alcohol in the form Industrial methylated spirit
– commonly use for skin disinfection.
 Pure alcohol – not disinfectant, but when diluted
with water 60-90% volume; it acts as bactericidal,
fungicidal, virucidal, tuberculocidal; but does not
destroy bacterial spore.
36

6. Formaldehyde
1. Formaldehyade soln
(formalin)-
 Effective against
vegetative bacteria, fungi
and many viruses.
Slowly effective against
bacterial spores (eg.
tetanus spore) and acid
fast bascilli.
Use – 2-3% soln(formalin
40%) for spraying room,
walls, furniture.
b. Formaldehyade
gas
Most commonly used
for disinfection of
rooms
books,bed, blanket
and other which can’t
boil
Operation theater
disinfection
37

7. Lime
Cheapest
Used in the form of fresh quick lime or 10-20%
aqueous suspension (milk of lime).
Uses
Faeces and urine disinfection within 2hrs ( by
mixing milk of lime)
Wall disinfection
As a deodorant lime is sprinkled in Cattle shed,
stables and urinals & latrines in public places.
38

8. Ethylene oxide
 Explosive, thus mixed with CO2
Uses –
 Heat sensitive articles – sterilize at 55-600C
 Kills bacteria, spores, viruses
 Sterilization of fabrics, plastic equipment,
cardiac catheters, books; but the process is
difficult.
39

9. Metals as microbicides
Anti infective activity of some heavy
metals known as Antiquity.
Ex. Silver – prophylaxis of conjunctivitis of
new born, topical therapy for burn wound.
Metals such as Silver, Iron, Copper are
used for environmental control,
disinfection of water
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10. Miscellaneous inactivating agents
2. Microwave
Radio frequency waves -
2450MHz
Used for disinfection of
 Soft contact lenses
 Dental instrument
 Urinary catheter
3. Ultra-violet radiation
Disinfection of drinking
water, air, titanium implants
1. Pasturization
4. Ozone
Drinking water disinfection
5. Flushing & washer
disinfectors
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Thank you!
42

Disinfection

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