Types of disinfectants & disinfection and sterilization

1. Sterilization and Disinfections

2. Introduction
A major risk of all surgical and nonsurgical
procedures performed in healthcare facilities is
the introduction of infection.
Failure to properly disinfect or sterilize
equipment carries not only the risk associated
with breach of the host barriers but also the
additional risk of person-to-person
transmission and transmission of
environmental pathogens.

3. Types of aseptic techniques
1. Medical asepsis.
2. Surgical asepsis.

4. Medical Asepsis
•Medical asepsis, or clean technique, involves
procedures and practices that reduce the
number and transmission of pathogens.

5. •Medical asepsis includes all the
precautionary measures necessary to prevent
direct transfer of pathogens from person to
person and indirect transfer of pathogens
through the air or on instruments, bedding,
equipment, and other inanimate objects.

6. Medical aseptic techniques include
1. frequent and thorough hand washing;
2. wearing of clean masks, gloves, and gowns
when appropriate;
3. proper cleaning of supplies and equipment;
4. disinfection;
5. proper disposal of needles, contaminated
materials, and infectious waste;
6. and sterilization.

7. Surgical asepsis
•Surgical asepsis, or sterile technique, includes
practices used to render and keep objects and
areas sterile (i.e., free of microbes).

8. Note the differences between medical and
surgical asepsis:
Medical asepsis is a clean technique, whereas
surgical asepsis is a sterile technique.
The goal of medical asepsis is to exclude
pathogens, whereas the goal of surgical
asepsis is to exclude all microbes

9. Surgical aseptic techniques are practiced in
•Operating rooms,
• in labor and delivery areas,
•and during invasive procedures: such as drawing
blood, injecting medications, urinary catheter
insertion, cardiac catheterization, Which must
be performed using strict surgical aseptic
precautions.

10. Surgical aseptic techniques include:
•surgical scrubbing of hands and fingernails
before entering the operating room;
•wearing sterile masks, gloves;
•using sterile solutions and dressings;
•using sterile drapes and creating a sterile field.

11. STERILIZATION AND DISINFECTION
The prevention of hospital infection depends in part
upon :
the availability of clean, and where necessary sterile,
equipment, instruments and dressings, isolation
facilities and the safe disposal of infected material.

12. •It must be stressed that the concept of sterility is
central to almost all areas of medical practice.
• An understanding of the rationale of sterilization and
disinfection will aid intelligent use of the range of
sterile equipment (from needles to prostheses) and
techniques (from surgery to hand washing) employed
in medical practice.

13. Cleaning
• Cleaning is the removal of foreign material (e.g., soil and
organic material) from objects.
• it is normally accomplished using water with detergents
or enzymatic products.
• It can be done manually (friction and . Fluidics) or using a
mechanical unit (e.g., ultrasonic cleaner, or washer
disinfector).

14. •Using friction (e.g., rubbing/scrubbing the soiled
area with a brush) is an old and dependable
method.
•Fluidics (i.e., fluids under pressure) is used to
remove soil and debris from internal channels
after brushing and when the design does not
allow the passage of a brush through a channel.
•Cleaning is done manually when the use area
does not have a mechanical unit or for fragile or
difficult-to-clean instruments.

15. Sterilization
Sterilization: is the process of killing or
removing all viable organisms.
 An item that is sterile is free from all viable
organisms – in this sense, viable means capable
of reproducing.

16. •Sterilization is achieved by
•Physical: by the removal of organisms from an
object. (High-pressure, saturated steam using an autoclave, or dry heat using an oven,
• are the most common and readily available methods used for sterilization.)
• or chemical means: by killing the organisms in
situ, sometimes leaving toxic breakdown
products (pyrogens) in the object.
• An alternative to high-pressure steam or dry-heat sterilization is chemical
sterilization (often called “cold sterilization”). If objects need to be
sterilized, but using high-pressure steam or dry-heat sterilization would
damage them or equipment is not available (or operational), they can be
chemically sterilized.

18. Disinfection
Disinfection is a process of removing or killing
most, but not all, viable organisms.

19. Methods of Disinfection :
•A chemical ‘disinfectant’, which kills
pathogens but may not kill viruses or spores,
or
•A physical process such as boiling water or
low-pressure steam, which reduces the load
of viable organisms.

20. Antiseptics
•Antiseptics are used to reduce the number of
viable organisms on the skin.
•Antiseptics are a particular group of disinfectants.
•Some act differentially, destroying the transient
flora but leaving untouched the normal skin flora
deep in the skin pores and hair follicles.

21. •It is impossible to sterilize the skin, but
thorough washing with antiseptic soaps can
reduce the numbers of organisms on the
surface considerably and therefore reduce
contact spread of infection. However, the
resident bacteria in the hair follicles and
ducts of sweat glands can recolonize the skin
surface within hours.

22. Pasteurization
Pasteurization can be used to eliminate pathogens in
heat-sensitive products.
Pasteurization reduces the total numbers of viable
microbes in bulk fluids such as milk and fruit juices
without destroying flavor and palatability. It does not
affect spores, but is effective against intracellular
organisms such as Brucella and mycobacteria and many
viruses.

23. Categories of Disinfectants
• A few disinfectants will kill bacterial spores
with prolonged exposure times (3–12 hours);
these are referred to as chemical sterilants.
• Other disinfectants used within healthcare
settings are categorized as high-level,
intermediate-level, and low-level disinfectants.

24. •High-level disinfectants kill all microbes (including
viruses), except large numbers of bacterial spores.
•Intermediate-level disinfectants might kill
mycobacteria, vegetative bacteria, most viruses,
and most fungi, but do not necessarily kill bacterial
spores.
•Low-level disinfectants kill most vegetative
bacteria, some fungi, and some viruses within 10
minutes of exposure.

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26. Disinfectants commonly used in healthcare settings

28. Spaulding System for Classification of
Instruments and Items for Patient Care
More than 30 years ago, Earle H. Spaulding devised a
system of classifying instruments and items for
patient care into three categories according to the
degree of risk for infection that was involved.
This system is still used to determine how these
items are to be disinfected or sterilized.

29. Spaulding System for Classification of
Instruments and Items for Patient Care
1- Critical items confer a high risk for infection
if they are contaminated with any microbe.
Thus, such objects must be sterile.

30. • Critical items include surgical instruments, cardiac and
urinary catheters, implants, and ultrasound probes
used in sterile body cavities.
• Items in this category should be purchased as sterile or
be sterilized using steam (preferably), ethylene oxide
gas, hydrogen peroxide gas plasma, or liquid chemical
sterilant.

31. Spaulding System for Classification of Instruments and
Items for Patient Care
2- Semi critical items contact mucous
membranes or non-intact skin and require
high-level disinfection.

32. • These include respiratory therapy and anesthesia
equipment, some endoscopes, laryngoscope blades,
esophageal manometry probes, cystoscopes, anorectal
manometry catheters, and diaphragm fitting rings.
• They minimally require high-level disinfection using
glutaraldehyde, hydrogen peroxide, ortho-
phthalaldehyde, or peracetic acid with hydrogen peroxide.

33. Spaulding System for Classification of Instruments and
Items for Patient Care
3- Noncritical items are those that come in contact
with intact skin, but not mucous membranes.
Such items are divided into two subcategories:
noncritical patient-care items (e.g., bedpans, blood
pressure cuffs, crutches, computers)
and noncritical environmental surfaces (e.g., bed rails,
bedside tables, patient furniture, floors).

34. •Low-level disinfectants may be used for noncritical
items.
•Any of the following disinfectants may be used for
noncritical items: 70% to 90% ethyl or isopropyl
alcohol, sodium hypochlorite (household bleach
diluted 1:500), phenolic germicidal detergent
solution, iodophor germicidal detergent solution,
and quaternary ammonium germicidal detergent
solution.

35. Deciding whether sterilization or disinfection
should be used
Sterilization and disinfection processes are costly, and so it is
important to choose the appropriate method and the one that
causes the least damage to the material involved.
A variety of considerations influence the choice of method. The
detailed mechanisms of the death process of microorganisms may
vary with the sterilizing technique used, but the net effect is
similar in that essential cell constituents (nucleic acids or proteins)
are inactivated.

36. The hospital should choose one or two clearly defined
and documented disinfectants that are:
easy to handle,
easy to understand and
easy to throw away after use.
the chemicals should not trigger allergies or other
illnesses.

37. Techniques for sterilization
Sterilization may be achieved by:
heat
irradiation (gamma or ultraviolet)
filtration
chemicals in liquid or gaseous phase
Other techniques of doubtful efficiency include freezing
and thawing, lysis, desiccation‫تجفيف‬, ultrasonication and
the use of electrical discharges, but these are not
applied in hospital practice.

38. 1- Heat:
•Exposure of the objects to heat will kills microbes
by coagulation of protein, denaturation of
enzymes and oxidation.
•Heat, as a way of transferring energy, is the
preferred choice for sterilization on the grounds
of ease of use, controllability, cost and efficiency.
•Dry heat sterilizes by oxidation of the cell
components. Incineration‫الحرق‬ and the use of
the laboratory Bunsen burner are examples of
sterilization by dry heat.

39. The most effective agent for sterilization is saturated
steam (moist heat) under pressure.
This can be achieved using an autoclave.
Steam under pressure aids penetration of heat into the
material to be sterilized (such as dressings), and there is a
direct relationship between temperature and steam
pressure. Steam under pressure has a temperature in
excess of 100°C, which results in increased killing of
microbes.

40. Uses of Moist heat in an autoclave is used to
sterilize:
-surgical instruments and
-dressings and
-heat-resistant pharmaceuticals.
-method for the sterilization of heat-sensitive
instruments such as endoscopes.

41. 2- Irradiation
Gamma irradiation energy is used to sterilize
large batches of small-volume items.
The use of gamma irradiation energy for
sterilization is an industrial process that works
well with products such as needles, syringes,
intravenous lines, catheters and gloves, and
even to prevent food spoilage.

42. •Irradiation can cause materials to deteriorate
and is thus not suitable for resterilization of
equipment.
•The killing mechanism involves the production
of free radicals, which break the bonds in DNA.

43. 3- Filtration
Sterilization through removing of microbes from fluids by
exposing to small size filter.
Used for sterilization of heat sensitive fluids like serum,
antibiotic, suger (glucose), urea, and Amino acids.
Filtration techniques are also used as a method for
quantifying bacteria in fluids.

44. 4- Chemical agents
The gases ethylene oxide and formaldehyde kill by
damaging proteins and nucleic acids.
Ethylene oxide and formaldehyde are examples of
alkylating gases:
Ethylene oxide has been widely used to sterilize
single-use medical requisites such as heart valves.
However, it is toxic and potentially explosive.

45. Formaldehyde is not explosive, but has an extremely
unpleasant odor and is an irritant to mucous
membranes.
oIt has been used as a disinfectant to decontaminate
rooms (such as isolation rooms) and in the laboratory
to disinfect exhaust-protective cabinets.
oA high relative humidity is essential for effective
killing.

46. •The liquid glutaraldehyde is used to disinfect
heat-sensitive articles.
oGlutaraldehyde is less toxic than formaldehyde
and can be stabilized in solution to remain active
for up to several weeks at in-use concentration.
oIt is used for the disinfection, but does not
sterilize, heat-sensitive articles such as
endoscopes and for inanimate surfaces.

47. •Hydrogen peroxide dry aerosol can be used
for infection outbreaks and as terminal
disinfection of isolates after infections with
effect on surfaces, air and inner parts of
mechanical equipment.

48. FACTORS AFFECTING THE EFFICACY
OF DISINFECTION AND STERILIZATION
•Number and Location of Microorganisms.
•Innate Resistance of Microorganisms.
•Concentration and Potency of Disinfectants.
•Physical and Chemical Factors.
•Organic and Inorganic Matter.
•Duration of Exposure.
•Biofilms.