Disinfectants

Dr. Jasminkumar Viramgami
Reader & H.O.D.,
Dept. of Swasthavritta,
Govt. Akhandanand Ayurved College, Ahmedabad, Gujarat

Definitions
A disinfectant or germicide is a
• substance which destroys harmful microbes
• (not usually spores)
• for Preventing transmission of disease.
• suitable only for in-animate objects.
Dr. J M Viramgami, HOD Swasthavritta,
GAAC

Definitions…
Antiseptic is a substance which
• destroys or inhibits the growth of micro
organisms.
• suitable for application to living tissues.
• disinfectant in low concentrations can act as an
antiseptic.
GAAC

Deodorant is a substance which
• suppresses or neutralizes bad odours,
• e.g., lime and bleaching powder.
Detergent is a surface cleaning agent
• which acts by lowering surface tension,
• e.g., soap removes bacteria along with dirt.
Sterilization is the
• process of destroying all life including spores.
• widely used in medical practice.
GAAC

Disinfectants
Their uses ranges from
• control of communicable diseases
• sterilization of instruments,
• treatment of infections of skin and mucous
membrane.
• the killing of infectious agents outside the
body
• by direct exposure to chemical or physical
agents.
GAAC

Types of Disinfections
concurrent
Pre-
current
Terminal
GAAC

Concurrent disinfection :
• Continuous disinfection
• agent is destroyed as soon as it is released from
the body and further spread is stopped.
• disinfection throughout the course of an illness.
• of urine, faeces, vomit, linen, clothes, hands,
(dressings, aprons, gloves, etc)
GAAC

Pre-current disinfection :
• Prophylactic disinfection
• Any infective organism is destroyed before the
item is used
• disinfection of water by chlorine,
pasteurization of milk and hand washing etc.
GAAC

Terminal disinfection:
• application measures in the last,
when patient is removed
• By recovery
• by death
• or to a hospital
• or has ceased to be a source of infection
• carried out along with airing and sunning of
rooms, furniture and bedding.
GAAC

NATURAL AGENTS
Sun Light: Direct and continuous exposure is
destructive to many disease producing
organisms.
• The ultraviolet rays are lethal to bacteria and
some viruses.
• linen, bedding, and furniture may be
disinfected by direct sunlight for several hours.
Air: Exposure to open air acts by drying or
evaporation of moisture which is lethal to
most bacteria.
GAAC

PHYSICAL AGENTS
Burning or Incineration:
• excellent method.
• For Inexpensive articles
(contaminated dressings,
rags and swabs can be
disposed off by burning).
• Faeces can be disposed off
by burning.
• not to be done in open air;
• best done in an incinerator.
GAAC

Hot air :
useful for sterilizing many articles
• (glassware, syringes, swabs, dressings, and
sharp instruments. )
• no penetrating power,
• not suitable for bulky articles such as
mattresses.
• Usually done in a hot air oven.
• temp should be maintained at 160-1800 C for
at least one hour to kill spores.
GAAC

Boiling : effective method
• provides an atmosphere of boiling and steam.
• suitable for small instruments, tools, linen and
rubber goods such as gloves.
• Boiling for about 30 min is adequate for linen,
utensils and bedpans.
• kill bacteria, but not spores or viruses.
• slow process,
• unsuitable for thick beddings and woollen
materials as they shrink.
GAAC

Physical agents...
Autoclaving :
• generate steam under pressure
(saturated steam)
• which is the most effective
sterilizing agent.
• Works as the pressure cooker.
• widely used in hospital and
laboratory practice.
• Steam attains a higher temp, and
greater powers of penetration
under pressure.Dr. J M Viramgami, HOD Swasthavritta,
GAAC

• It destroys all forms of life, including spores.
• most effective for linen, dressings, gloves,
syringes, certain instruments and culture
media.
• not suitable for sterilization of plastics and
sharp instruments.
GAAC

Physical agents...
Radiation : Ionizing radiation
• one of the most viable, safe and economic
methods
• great penetrating powers.
• most effective, but costly.
• Commercially done by gamma radiation.
• used for sterilization of bandages, dressings,
catgut and surgical instruments.
• It requires special packing and equipment.
objects are placed in plastic bags for radiation.
they remain sterile until opened.Dr. J M Viramgami, HOD Swasthavritta,
GAAC

CHEMICAL AGENTS
• Articles which cannot be sterilized by boiling
or autoclaving
• may be immersed in chemical disinfectants.
• also used for the disinfection of faeces, urine
and other contaminated material.
GAAC

1.Phenol and related compounds
Phenol : Pure phenol is used as a standard.
Crude phenol : mixture of phenol and cresol.
effective against
• gram +ve and -ve bacteria; certain viruses.
• slow against spores and acid-fast bacteria.
• used for mopping floors and cleaning drains.
• effect is weakened by dilution.
• Aqueous solutions of 0.2 to 1 % are bacterio-
static. Dr. J M Viramgami, HOD Swasthavritta,
GAAC

GAAC

Cresol :
• coal-tar disinfectant.
• 3 to 10 times powerful than phenol,
• yet no more toxic.
• used in 5 to 10 % strength for disinfection of
faeces and urine.
• all-purpose general disinfectant.
GAAC

Cresol emulsions :
• Cresol emulsified with soap
• known as "saponified cresol".
• very powerful disinfectants.
• Lysol, Izal and Cyllin are cresol emulsions.
• 2 % solution of Lysol may be used for
disinfection of faeces.
GAAC

Chlorhexidine
(hibitane) :
• most useful skin antiseptics.
• active against vegetative gram +ve organisms
• inactivated by soaps and detergents.
• alcoholic or aqueous solutions used as effective
hand lotions.
• 1 % chlorhexidine Creams and lotions are
recommended for burns and hand disinfection.
GAAC

Hexachlorphane :
• highly active against gram-positive organisms,
• less active against gram-negative.
• slow in action,
• cumulative effect on the skin
• compatible with soaps
• included in soap preparation without loss of
activity.
GAAC

Dettol (chloro-xylenol):
• relatively non-toxic antiseptic.
• used safely in high concentrations.
• easily inactivated by organic matter.
• active against streptococci,
• worthless against some gram-negative
bacteria.
GAAC

• suitable for disinfection of
instruments and plastic
equipment;
• a contact of at least 15 min.
required for disinfection.
GAAC

Savlon :
• combination of Cetrimide
and hibitane.
• Plastic appliances may be
disinfected by keeping them
in savlon for 20 mins.
• Clinical thermometers may be
best disinfected in savlon in
spirit solution in under 3 mins.
2. Quaternary ammonia compounds
GAAC

Cetrimide :
• actively bactericidal against vegetative gram +ve
organisms,
• much less against gram -ve.
• soluble in water.
• it has a soapy feel.
• used in 1-2 % strength.
GAAC

3.Halogens and their compounds
• halogens are actively bactericidal agents
• only useful antiseptics with a sporocidal
action.
• rapidly inactivated by organic matter.
GAAC

Bleaching powder :
• chlorinated lime powder
with a smell of chlorine.
• contains about 33 % of
"available chlorine".
• unstable compound
• loses its chlorine content
on storage
GAAC

• kills most of the organisms when used in the
strength of 1 to 3 %.
• widely used in public health practice for
disinfection of water, faeces and urine;
• as a deodorant.
• A 5 % solution is suitable for disinfection of
faeces and urine allowing a
period of one hour for
disinfection.
GAAC

Sodium hypochlorite :
• acts in the same way as bleaching powder,
• but is stronger.
• It corrodes metals.
• A freshly prepared hypo solution
recommended for sterilizing infant's feeding
bottles.
GAAC

Halazone tablets :
• These are chlorine tablets.
• 1 tab of halazone containing 4
mg of halazone
• sufficient to disinfect about 1
litre of water in about 1/2 to 1
hour.
GAAC

Iodine :
• alcoholic solution is tincture Iodine.
• most effective skin antiseptics.
• Plastic appliances may be sterilized
by keeping in aqueous solution of
iodine.
• cheap, readily available and quick in
action.
• for disinfection of drinking water in
an emergency. A drop of tincture
iodine may be added to a litre.
GAAC

Iodophors :
• complex of iodine and
"solubilizers"
• Povidone iodine-
Betadine
• same activity as iodine,
but non-irritant
• do not stain the skin
GAAC

Alcohols
• Ethyl and isopropyl alcohols
• commonly used as antiseptics and
disinfectants.
• expense and flammable
• limited to small article disinfection.
most effective skin antiseptics are
• alcoholic solutions of chlorhexidine and iodine.
GAAC

Ethyl alcohol (methylated spirit)
• most commonly used for skin disinfection and
hand washing.
• Pure alcohol has no powers of disinfection
when diluted to 70 % strength,
• it is a good antiseptic.
• lethal to non-sporing bacteria.
• Lacks activity against bacterial spores
• But inactivate viruses.
GAAC

Formaldehyde (formalin)
• effective against
vegetative bacteria,
fungi and many viruses
• slowly effective against
bacterial spores (e.g.
tetanus spores) and
acid-fast bacteria.
• It does not injure fabrics
and metals.
GAAC

• highly toxic and irritant gas.
• commonly used for disinfection of rooms. (for
spraying rooms, walls and furniture.)
• gas may be used for disinfection of blankets,
beds, books and other valuable articles which
cannot be boiled.
• Laboratories
• To ripe fruits
GAAC

Miscellaneous
Lime :
• cheapest disinfectant.
• used in the form of fresh quick lime
• aqueous suspension as "milk of lime".
• Faeces and urine can be disinfected by mixing
aqueous suspension of lime
• used for treating walls.
• As a deodorant, sprinkled in cattle sheds and in
public places where urinal and latrines are
located.
GAAC

Soap:
• good cleansing agent for hands
and the body.
• washes off dust and bacteria by
its detergent action.
• Hot water enhance the action
of soap.
GAAC

Potassium permanganate:
• weak disinfectant.
• used to wash vegetables,
fruits, and utensils.
(1:1000 solution )
• Sometimes it is used to
disinfect drinking water.
GAAC

Recommended
disinfection
procedures
GAAC

1. Faeces and urine
disinfected by
• adding an equal volume of one of the
disinfectants. allow to stand for 1-2 hours.
• equal amount of quick-lime or freshly prepared
milk of lime may be added, mixed and left for 2
hours.
• a bucket of boiling water may be added to the
faeces which is then covered and allowed to
stand until cool.
GAAC

After disinfection,
• excretal matter may be emptied into water
closet or buried in ground.
Bedpans and urinals
• ideally be steam disinfected.
• Alternatively, may be disinfected with 2.5%
cresol for an hour after cleaning.
GAAC

2. Sputum
• best destroyed by burning.
• If the amount is considerable (as in TB
hospitals), it may be disinfected by boiling or
autoclaving for 20 mins at 20 lbs pressure.
• the patient may be asked to spit in a sputum
cup half filled with 5 % cresol.
• cup is allowed to stand for an hour and the
contents may be emptied and disposed off.
GAAC

3. Room
cleaning, airing and exposure to direct sunlight,
for several hours will be sufficient.
For chemical disinfection,
• floors and hard surfaces to be sprayed or
mopped with one of the disinfectants.
(chlorinated lime; formaldehyde solution;
phenolic disinfectants such as cresol).
• The solution should remain in contact with the
surface for at least 4 hours before final washing.
GAAC

when Fumigation is required,
• the gas mostly used is formaldehyde.
• The room is kept closed for 6-12 hours to
allow disinfection.
• Formaldehyde is most effective at a high temp
and a relative humidity of 80-90 %.
GAAC

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Disinfectants

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