are antimicrobial agents that are applied to non-living objects to destroy microorganisms that are living on the objects.Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical and/or chemical process that kills all types of life.
2. What is DisinfectionWhat is Disinfection
Disinfection may be defined as:
Cleaning an article of some or all
of the pathogenic organisms
which may cause infections.
3. DEFINITIONS
Antisepsis: the practice of using antiseptics to: the practice of using antiseptics to
eliminate the microorganisms that cause diseaseeliminate the microorganisms that cause disease..
Asepsis: the absence of bacteria, viruses, and other
microorganisms.
Aseptic technique: is a procedure used by medical
staff to prevent the spread of infection. The goal is
to reach asepsis, which means an environment that
is free of harmful microorganisms.
4. Antiseptics versus Disinfectants
Antiseptics:
• chemicals that kill microorganisms on living skin or
mucous membranes.
• Use on skin and mucous membranes to kill
microorganisms
• Not for use on inanimate objects
Disinfectants:
• Use to kill microorganisms on inanimate objects.
• Not for use on skin or mucous membranes.
5. Cleaning - Decontamination- Decontamination
Cleaning
• the physical removal of foreign
material, e.g., dust, soil, organic
material such as blood,
secretions, excretions and
microorganisms.
• Cleaning generally removes
rather than kills microorganisms.
It is accomplished with water,
detergents and mechanical
action.
• Cleaning reduces or eliminates
the reservoirs of potential
pathogenic organisms
Decontamination
• the removal of disease producing
microorganisms to leave an item
safe for further handling.
6. Chemical DisinfectionChemical Disinfection
Bactericidal - chemical agents capable of killing
bacteria. Similarly agents that are virucidal,
fungicidal or sporicidal are agents capable of
killing these organisms.
Bacteriostatic - Chemical agents that inhibit the
growth of bacteria but do not necessarily kill
them.
7. High level disinfection
High level disinfection processes destroy
vegetative bacteria, mycobacteria, fungi
and enveloped (lipid) and nonenveloped
(non lipid) viruses, but not necessarily
bacterial spores. High level disinfectant
chemicals (also called chemical sterilants)
must be capable of sterilization when
contact time is extended. Items must be
thoroughly cleaned prior to high level
disinfection.
9. Low level disinfection
Low level disinfectants kill most vegetative
bacteria and some fungi as well as enveloped
(lipid) viruses (e.g., hepatitis B, C, hantavirus,
and HIV). Low level disinfectants do not kill
mycobacteria or bacterial spores. Low level
disinfectants are typically used to clean
environmental surfaces.
10. Disinfection
• Alcohols
• Chlorine and Chlorine compounds
• Formaldehyde
• Glutaraldehyde
• Ortho-phthalaldehyde,
• Hydrogen peroxide
• Iodophors
• Peracetic acid
• Phenolics
• Quaternary ammonium compounds.
Many disinfectants are used alone or in
combinations in the health-care setting.
11. Disinfectant effectiveness
depends on many factors
• Type of contaminating microorganism. Each disinfectant has
unique antimicrobial attributes.
• Degree of contamination. This determines the quality of
disinfectant required and time of exposure.
• Amount of proteinaceous material present. High protein based
materials absorb and neutralize some chemical disinfectants.
• Presence of organic matter and other compounds such as
soaps may neutralize some disinfectants.
• Chemical nature of disinfectant. It is important to understand
the mode of action in order to select the appropriate
disinfectant.
12. Disinfectant effectiveness depends on many factors
• It is important to choose the proper concentration and quantity
of disinfectant that is best suited to each situation.
• Contact time and temperature. Sufficient time and appropriate
temperature must be allowed for action of the disinfectant and
may depend on the degree of contamination and organic matter
load.
• Residual activity and effects on fabric and metal should be
considered for specific situations.
• Application temperature, pH and interactions with other
compounds must be considered.
• Toxicity to the environment and relative safety to people that
may be exposed.
13. Alcohol
denaturation of proteins
• Alcohols are commonly used topical antiseptics. Rapid
bactericidal, tuberculocidal, fungicidal, and virucidal but
do not destroy bacterial spores.
• optimum bactericidal concentration is 60%–90%
solutions in water.
• Alcohols are not effective against bacterial spores and
have limited effectiveness against nonenveloped
viruses.
• They are also used to disinfect the surface of medical
equipment. Alcohols require time to work and they may
not penetrate organic material.
14. Chlorine and Chlorine Compounds
(Hypochlorits(
•They have a broad spectrum of antimicrobial activity, do
not leave toxic residues, are unaffected by water hardness.
•Hypochlorite, the most widely used of the chlorine
disinfectants, are available as liquid or solid.
•The most common chlorine products in are aqueous
solutions of 4 to 6% sodium hypochlorite, which are readily
available as “household bleach”.
•Hypochlorits Most recommended in They are included in
most recommendation for decontamination of hepatitis and
AIDS viruses .
•Hypochlorits are also the agent of choice in disinfecting
surfaces used for food preparation or in bathrooms.
Organic material such as feces or blood inactivate chlorine
based disinfectants, therefore, surfaces must be clean
before their use.
15. • Formaldehyde is used as a disinfectant and sterilants in both its
liquid and gaseous states.
• The aqueous solution is a bactericide, tuberculocide, fungicide,
virucidal and sporicidal.
• Mode of Action. Formaldehyde inactivates microorganisms by
alkalizing the amino and sulfhydral groups of proteins and ring
nitrogen atoms of purine bases.
• Be careful in handling Formaldehyde, wear mask (irritant and
potential carcinogenic )
Formaldehyde
formalin
16. Glutaraldehyde
high-level disinfectant and chemical sterilant
• Aldehydes have a wide germicidal spectrum. Gluteraldehydes are
bactericidal, virucidal, fungicidal, sporicidal and parasiticidal.
• They are used as a disinfectant or sterilant in both liquid and
gaseous forms.
• Glutaraldehyde is used most commonly as a high-level disinfectant
for medical equipment such as endoscopes.
• Glutaraldehyde should not be used for cleaning Noncritical surfaces
because it is too toxic and expensive.
17. Hydrogen Peroxide
3% hydrogen peroxide is a stable and effective
disinfectant when used on inanimate surfaces.
• Peroxides such as hydrogen peroxide are often used as
antiseptics to clean wounds.
• The activity of peroxides is greatest against anaerobic
bacteria. Hydrogen peroxide at high concentrations is in
some cases is damaging to tissues, resulting in a
prolonged healing time.
• It is useful for cleaning surgical sites after closure, but
use sparingly to avoid penetrating suture lines, which
would inhibit healing.
18. Iodophors
Iodine solutions
• The best-known and most widely used iodophor is povidone-iodine.
• Mode of Action. Iodine can penetrate the cell wall of microorganisms
quickly, and the lethal effects are believed to result from disruption of protein
and nucleic acid structure and synthesis.
19. Ortho-phthalaldehyde (OPA(
• Ortho-phthalaldehyde is a high-level disinfectant
• OPA solution is a clear, pale-blue liquid with a pH of 7.5.
• advantages :excellent stability over a wide pH range (pH 3–9(
• not a known irritant to the eyes and nasal passages, does not
require exposure monitoring, has a barely perceptible odor
20. Peracetic Acid
• rapid action against all microorganisms.
• Special advantages of peracetic acid are that it lacks
harmful decomposition products
• It remains effective in the presence of organic matter and is
sporicidal even at low temperatures
• Uses. An automated machine using peracetic acid to chemically
sterilize medical (e.g., endoscopes, arthroscopes(, surgical, and
dental instruments.
• Peracetic Acid and Hydrogen Peroxide
• combination of peracetic acid and hydrogen peroxide
inactivated all microorganisms except bacterial spores within
20 minutes.
• The 0.08% peracetic acid plus 1.0% hydrogen peroxide
product effectively inactivated glutaraldehyde-resistant
mycobacteria.
21. Phenolics
• In high concentrations, phenol acts as a gross protoplasmic poison,
penetrating and disrupting the cell wall and precipitating the cell proteins.
• Phenolics are bactericidal, fungicidal, virucidal, and tuberculocidal (low
level disinfectant(
• disinfectants for use on environmental surfaces (e.g., bedside tables,
bedrails, and laboratory surfaces( and noncritical medical devices.
• hyperbilirubinemia in infants placed in bassinets where phonetic
detergents were used , bilirubin levels were reported to increase in
phenolic-exposed infants.
should not be used to clean infant
bassinets and incubators while occupied.
22. Quaternary Ammonium Compounds
• The quaternary ammonium compounds are widely used as disinfectants.
• quaternaries are good cleaning agents.
• Mode of Action. The bactericidal action of the quaternaries has been
attributed to the inactivation of energy-producing enzymes, denaturation of
essential cell proteins, and disruption of the cell membrane.
• Uses. The quaternaries commonly are used in ordinary environmental
sanitation of Noncritical surfaces, such as floors, furniture, and walls.
23. Chlorhexidine
Chlorhexidine products are often used as disinfectants
for inanimate objects or antiseptics for cleaning
skin wounds.
• Skin Antisepsis: 0.5% Chlorhexidine Skin
Preparation with Alcohol.
• Low toxicity
• Used in disinfection of the skin and hands
and mucous membranes
24. No Disinfectant is substitute forNo Disinfectant is substitute for
the following Proceduresthe following Procedures
• Hand washing (hand hygiene)
• The use of personal protective equipment (e.g.
gloves) when handling blood, body substances
excretions and secretions.
• Appropriate handling of patient care equipment
and soiled linen;
• The prevention of needle stick/sharp injuries.
• Environmental cleaning
• Appropriate handling of waste and
• Taking care of yourself (e.g. immunization)
25. Hand Washing
Yet no substitute for washing hands
Do not forget to Wash Your HandsDo not forget to Wash Your Hands
Immediately on arrival at workImmediately on arrival at work
Before and after examining each clientBefore and after examining each client
After touching anything that might be contaminatedAfter touching anything that might be contaminated
After handling specimensAfter handling specimens
Before putting on gloves for clinical proceduresBefore putting on gloves for clinical procedures
After removing glovesAfter removing gloves
After using the toilet or latrineAfter using the toilet or latrine
Before leaving workBefore leaving work