2. A tribute to Ignaz SemmelweisA tribute to Ignaz Semmelweis
3. A Hygienic and Scientific HandA Hygienic and Scientific Hand
Washing continues to be bestWashing continues to be best
prayer in the Hospitalprayer in the Hospital
4. What is DisinfectionWhat is Disinfection
DisinfectionDisinfection may be defined as:may be defined as: Cleaning anCleaning an
article of some or all of the pathogenicarticle of some or all of the pathogenic
organisms which may cause infectionorganisms which may cause infection
Perfect disinfectant would also offer completePerfect disinfectant would also offer complete
and full sterilization, without harming otherand full sterilization, without harming other
forms of life, be inexpensive, and non-corrosive.forms of life, be inexpensive, and non-corrosive.
Unfortunately ideal disinfectants do not exist.Unfortunately ideal disinfectants do not exist.
Most disinfectants are also, by their very nature,Most disinfectants are also, by their very nature,
potentially harmful (even toxic) to humans orpotentially harmful (even toxic) to humans or
animals.animals.
6. TerminologyTerminology
AntisepsisAntisepsis: chemical destruction of: chemical destruction of
vegetative pathogens on living tissuevegetative pathogens on living tissue
Degerming:Degerming: mechanical removal ofmechanical removal of
microbes from limited areamicrobes from limited area
Sanitization:Sanitization: lowering microbial countslowering microbial counts
on eating and drinking utensils to safeon eating and drinking utensils to safe
levelslevels
9. AntisepticsAntiseptics versusversus DisinfectantsDisinfectants
Antiseptics:Antiseptics:
Use on skin and mucous membranes to killUse on skin and mucous membranes to kill
microorganismsmicroorganisms
NotNot for use on inanimate objectsfor use on inanimate objects
Disinfectants:Disinfectants:
Use to kill microorganisms on inanimateUse to kill microorganisms on inanimate
objectsobjects
NotNot for use on skin or mucousfor use on skin or mucous
membranesmembranes
10. Chemicals – DisinfectionChemicals – Disinfection
Antiseptics - chemicals that kill microorganisms
on living skin or mucous membranes.
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.
11. Cleaning
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. The terms “decontamination”
and “sanitation” may be used for this process in
certain settings, e.g., central service or dietetics.
Cleaning reduces or eliminates the reservoirs of
potential pathogenic organisms
13. Disinfection
Disinfection: the inactivation of disease-
producing microorganisms. Disinfection
does not destroy bacterial spores.
Disinfectants are used on inanimate
objects in contrast to antiseptics, which
are used on living tissue. Disinfection
usually involves chemicals, heat or
ultraviolet light. The nature of chemical
disinfection varies with the type of product
14. 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.
16. 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.
17. Chemical MethodsChemical Methods
Disinfectants andDisinfectants and
antisepticsantiseptics
Surface-active agentsSurface-active agents
(surfactants)(surfactants)
Chemical foodChemical food
preservativespreservatives
AldehydesAldehydes
Gas sterilizationGas sterilization
Oxidizing agentsOxidizing agents
[Antibiotics][Antibiotics]
18. DisinfectantsDisinfectants
Kill/inhibit growth of microbes onKill/inhibit growth of microbes on
surfacessurfaces
Phenols and phenolics: damage lipidPhenols and phenolics: damage lipid
membranesmembranes
– Active in presence of organic matterActive in presence of organic matter
– StableStable
– Persist for long periods afterPersist for long periods after
applicationapplication
20. AntisepticsAntiseptics
Alcohol : proteinAlcohol : protein
denaturation anddenaturation and
membrane damagemembrane damage
– evaporate quicklyevaporate quickly
– ethanol andethanol and
isopropanolisopropanol
– [not effective if taken[not effective if taken
internally]internally]
21. DisinfectantsDisinfectants
Halogens: iodine and chlorineHalogens: iodine and chlorine
– Iodine used in solution : BetadineIodine used in solution : Betadine®® andand
IsodineIsodine®®
– Chlorine is a gas that forms bleachChlorine is a gas that forms bleach
(hypochlorite) in water(hypochlorite) in water
– Chloramines are chlorine and ammoniaChloramines are chlorine and ammonia
23. Sterilization – An absoluteSterilization – An absolute
ProcedureProcedure
The destruction of all
forms of microbial life
including bacteria,
viruses, spores and
fungi. Items should
be cleaned thoroughly
before effective
sterilization can take
place.
24. Noncritical items
That either come in
contact with only
intact skin but not
mucous membranes
or do not directly
contact the patient.
Reprocessing of
noncritical items
involves cleaning and/
or low level
disinfection
25. Sanitation
Process that reduces
microorganisms on an
inanimate object to a
level below that of
infectious hazard
(e.g., dishes and
eating utensils are
sanitized
26. Semi critical items
Devices that come in
contact with no intact
skin or mucous
membranes but
ordinarily do not
penetrate them.
Reprocessing semi
critical items involves
meticulous cleaning
followed preferably by
high-level disinfection
27. 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.
28. Disinfectant effectiveness depends
on many factors.
Concentration and quantity of disinfectant. 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.
• Cost.
30. PHENOLICS
Examples: Benzyl-4-chlorophenol, Amyl
phenol, Phenyl phenol
Advantages and disadvantages: good
general purpose disinfectants, not readily
inactivated
by organic matter, active against wide
range of organisms (including
mycobacterium), but not sporicidal.
31. Phenol as Disinfectant
Phenolic disinfectants are
effective against bacteria
(especially gram positive
bacteria) and enveloped
viruses. They are not
effective against
nonenvelopedd viruses
and spores. These
disinfectants maintain
their activity in the
presence of organic
material.
32. Phenol as Disinfectant
They are not effective
against nonenvelopedd
viruses and spores. These
disinfectants maintain
their activity in the
presence of organic
material. This class of
compounds is used for
decontamination of the
hospital environment,
including laboratory
surfaces, and noncritical
medical items
33. Phenol as Disinfectant
Phenolics are not
recommended for semi
critical items because of
the lack of validated
efficacy data for many of
the available formulations
and because the residual
disinfectant on porous
materials may cause
tissue irritation even
when thoroughly rinsed.
34. Alcohols
“Alcohol" refers to two water-soluble chemicals:
ethyl alcohol and isopropyl alcohol. These
alcohols are rapidly bactericidal rather than
bacteriostatic against vegetative forms of
bacteria (Gram + and Gram -); they also are
tuberculocidal, fungicidal, and virucidal against
enveloped viruses. Alcohols are not effective
against bacterial spores and have limited
effectiveness against nonenveloped viruses
35. Alcohols
Their cidal activity drops
sharply when diluted
below 50% concentration
and the optimum
bactericidal concentration
is in the range of 60-90%
solutions in water
(volume/volume). The
antimicrobial activity of
alcohols can be attributed
to their ability to
denature proteins.
37. Alcohols
Alcohols are
commonly used
topical antiseptics.
They are also used to
disinfect the surface
of medical equipment.
Alcohols require time
to work and they may
not penetrate organic
material.
38. Alcohols
They also evaporate
rapidly which makes
extended exposure time
difficult to achieve unless
the items are immersed.
Alcohol irritates tissues.
They are generally too
expensive for general use
as a surface disinfectant
39. Soap, Water and common senseSoap, Water and common sense
are yet the best antisepticsare yet the best antiseptics
William OslerWilliam Osler
40. Gaining importance in HandGaining importance in Hand
Washing with AlcoholsWashing with Alcohols
The use of either ethyl
alcohol or isopropyl
alcohol in a 60-90%
solution has recently
gained wide acceptance
in health care settings as
hand antiseptics. They
can be used as a
reasonable substitute for
handwashing as long as
hands are not visibly
soiled
41. Hypochlorite's
Hypochlorites are the most widely used of
the chlorine disinfectants and are available
in a liquid (e.g. sodium hypochlorite) or
solid (e.g. calcium hypochlorite, sodium
dichloroisocyanurate) form. The most
common chlorine products in are aqueous
solutions of 4 to 6% sodium hypochlorite,
which are readily available as “household
bleach”.
42. Hypochlorite's
They have a broad
spectrum of
antimicrobial activity,
are unaffected by
water hardness, are
inexpensive and fast
acting, and have a
low incidence of
serious toxicity
43. Hypochlorite's
Other disadvantages of
hypochlorites include
corrosiveness to metals in
high concentrations
(>500 ppm), inactivation
by organic matter,
discoloring or “bleaching”
of fabrics, and release of
toxic chlorine gas when
mixed with ammonia or
acid.
44. Hypochlorite's
Hypochlorites can eliminate both enveloped and
nonenveloped viruses if used in correct dilution
and contact time. They are also is effective
against fungi, bacteria, and algae but not
spores. Household bleach is typically diluted
using 1:50 with water (1000ppm) for surface
disinfection. Bleach solutions have been
recommended for use in both hospitals and the
community as disinfecting solutions.
46. Hypochlorite's
Hypochlorites 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.
48. Iodine And Iodophor
Disinfectants
These compounds have
been incorporated in time
release formulations and
in soaps (surgical scrubs).
Simple iodine tinctures
(dissolved in alcohol)
have limited cleaning
ability. These compounds
are bactericidal,
sporicidal, virucidal and
fungicidal but require a
prolonged contact time.
49. Iodine And Iodophor
Disinfectants
Besides their use as
an antiseptic,
iodophors have been
used for the
disinfection of blood
culture bottles and
medical equipment
such as hydrotherapy
tanks, thermometers,
and endoscopes
50. Iodine And Iodophor
Disinfectants
The disinfective ability of
iodine, like chlorine, is
neutralized in the
presence of organic
material and hence
frequent applications are
needed for thorough
disinfection. Iodine
tinctures can be very
irritating to tissues, can
stain fabric and be
corrosive.
52. Hydrogen Peroxide
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.
53. Hydrogen Peroxide
Stabilized hydrogen
peroxides can be used to
disinfect environmental
surfaces. The literature
contains several accounts
of the properties,
germicidal effectiveness,
and potential uses for
stabilized hydrogen
peroxide in the hospital
setting
54. Hydrogen Peroxide
Stabilized peroxides
may also be blended
with iodophors or
quaternary ammonia.
Hydrogen peroxide is
also blended with
paracetic acid in high
concentrations for use
as a high-level
disinfectant
55. Gluteraldehyde
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. They
have moderate residual
activity and are effective
in the presence of limited
amounts of organic
material
56. Formaldehyde
Gluteraldehydes are very
potent disinfectants,
which can be highly toxic.
Use them only as a last
resort and then under
trained supervision in a
well-ventilated setting
and with appropriate
personal protective
equipment.
57. Formaldehyde
Formaldehyde is used as
a disinfectant and
sterilant both in the liquid
and gaseous states.
Formaldehyde is sold and
used principally as a
water-based solution
called formalin, which is
37% formaldehyde by
weight. The aqueous
solution is bactericidal,
tuberculocidal, fungicidal,
virucidal and sporicidal
58. Formaldehyde
Formaldehyde should be
handled in the workplace as a
potential carcinogen with an
employee exposure standard
that limits an 8 hour time-
weighted average exposure to
a concentration of 0.75 ppm.
For this reason,
employees should
have limited direct
contact with
formaldehyde and
these considerations
limit its role in
sterilization and
disinfection processes
59. Ortho-phthalaldehyde
Ortho-phthalaldehyde (OPA) is a chemical
sterilant similar to Gluteraldehydes with similar
antimicrobial activity. OPA has several potential
advantages compared to Gluteraldehydes. It has
excellent stability over a wide pH range (pH
3-9), is not a known irritant to the eyes and
nasal passages, does not require exposure
monitoring, has a barely perceptible odor, and
requires no activation. OPA, like
Gluteraldehydes, has excellent material
compatibility
60. Ortho-phthalaldehyde
A potential disadvantage of OPA is that it
stains proteins gray (including unprotected
skin) and thus must be handled with
caution. However, skin staining would
indicate improper handling that requires
additional training and/or personal
protective equipment (PPE) (gloves, eye
and mouth protection, fluid-resistant
gowns).
61. Per acetic Acid
Peracetic, or peroxyacetic, acid is
characterized by a very rapid action
against all microorganisms. A special
advantage of peracetic acid is it has no
harmful decomposition products (i.e.,
acetic acid, water, oxygen, hydrogen
peroxide) and leaves no residue. It
remains effective in the presence of
organic matter and is sporicidal even at
low temperatures
62. Per acetic Acid
It is used in
automated machines
to chemically sterilize
medical, surgical, and
dental instruments
(e.g., endoscopes,
arthroscopes).
63. Per acetic Acid and Hydrogen
Peroxide
Two chemical sterilants are available that
contain peracetic acid plus hydrogen
peroxide (0.08 peracetic acid plus 1.0%
hydrogen peroxide [no longer marketed],
0.23% peracetic acid plus 7.35%
hydrogen peroxide). The bactericidal
properties of peracetic acid and hydrogen
peroxide have been established.
64. Per acetic acid and hydrogen
peroxide useful in Hemodialyzers
Findings demonstrated
that this product
inactivated all
microorganisms with the
exception of bacterial
spores within 20 minutes.
The combination of per
acetic acid and hydrogen
peroxide has been used
for disinfecting hem
dialyzers.
65. Quaternary Ammonium
Compounds
The quaternaries are good cleaning agents
but high water hardness and materials
such as cotton and gauze pads may make
them less microbiocidal because these
materials absorb the active ingredients. As
with several other disinfectants (e.g.,
phenolics, iodophors) gram-negative
bacteria have been found to survive or
grow in these preparations
66. Quaternary Ammonium
Compounds
They are not effective against non-enveloped
viruses, fungi and bacterial spores. QA
disinfectants carry a very strong positive charge
that makes good contact with negatively
charged surfaces. This characteristic makes most
very good cleaning agents. QA compounds are
generally low in toxicity, but prolonged contact
can be irritating. The quaternaries are commonly
used in ordinary environmental sanitation of
noncritical surfaces such as floors, furniture, and
walls
67. Work with CautionWork with Caution
A wide range of microorganisms is
destroyed by varying concentrations of
aqueous formaldehyde solutions. Although
formaldehyde-alcohol is a chemical
sterilant and formaldehyde is a high-level
disinfectant, the hospital uses of
formaldehyde are limited by its irritating
fumes and the pungent odor that is
apparent at very low levels (<1 ppm).
69. What is Gas PlasmaWhat is Gas Plasma
Plasma is aPlasma is a fourth state of matterfourth state of matter which iswhich is
distinguishable from liquid, solid, or gas.distinguishable from liquid, solid, or gas.
In nature, plasma is widespread in outerIn nature, plasma is widespread in outer
space.space.
Gas plasma generated in an enclosedGas plasma generated in an enclosed
chamber under deep vacuum using Radiochamber under deep vacuum using Radio
frequency or Microwave emery to excitefrequency or Microwave emery to excite
gas molecules are produced chargedgas molecules are produced charged
particlesparticles
70. How Gas Plasma works.How Gas Plasma works.
Many particles are in the form of free radicalsMany particles are in the form of free radicals
A free radical is an Atom with an unpairedA free radical is an Atom with an unpaired
electron and is a highly reactive specieselectron and is a highly reactive species
The mechanism of action of this device is theThe mechanism of action of this device is the
production of free radicals within a plasma fieldproduction of free radicals within a plasma field
that are capable of interacting with essential cellthat are capable of interacting with essential cell
components, ie is enzymes and nucleic acids.components, ie is enzymes and nucleic acids.
And thereby disrupt the metabolism ofAnd thereby disrupt the metabolism of
microorganisms.microorganisms.
71. Gas Plasma - SterilizationGas Plasma - Sterilization
Plasma sterilizationPlasma sterilization
operates differentlyoperates differently
because of its specificbecause of its specific
active agents, which areactive agents, which are
ultraviolet (UV) photonsultraviolet (UV) photons
and radicals (atoms orand radicals (atoms or
assembly of atoms withassembly of atoms with
unpaired electrons,unpaired electrons,
therefore chemicallytherefore chemically
reactive, e.g., O and OH,reactive, e.g., O and OH,
respectivelyrespectively
72. BASIC MECHANISMS OFBASIC MECHANISMS OF
PLASMA STERILIZATIONPLASMA STERILIZATION
Destruction by UV irradiation of theDestruction by UV irradiation of the
genetic material of the microorganism;genetic material of the microorganism;
this is a statistical process requiring athis is a statistical process requiring a
sufficient number of lesions of the DNAsufficient number of lesions of the DNA
strands.strands.
Erosion of the microorganism, atom byErosion of the microorganism, atom by
atom, through intrinsic photo desorptionatom, through intrinsic photo desorption
73. Advantage of the plasma method
An advantage of the plasma method is the
possibility, under appropriate conditions,
of achieving such a process at relatively
low temperatures (≤50 °C), preserving
the integrity of polymer-based
instruments, which cannotbe subjected to
autoclaves and ovens
Furthermore, plasma sterilization is safe,
both for the operatorand the patient, in
contrast to EtO.
74. Hydrogen Peroxide SterilizationHydrogen Peroxide Sterilization
Offers Fast Cycle TimesOffers Fast Cycle Times
Benefits of gasBenefits of gas
plasma (vaporizedplasma (vaporized
hydrogen peroxide)hydrogen peroxide)
sterilization are faststerilization are fast
cycle times, thecycle times, the
absence of toxicabsence of toxic
residuals, and a low-residuals, and a low-
moisture environmentmoisture environment
not exceeding 50ºC, anot exceeding 50ºC, a
75. NewNew CDCCDC guidelinesguidelines
Factors Related To Infection Risk
Endoscope
contamination
accounts for more
health care related
infections than any
other medical
instrument and is
responsible for
consequences ranging
from bacterial
colonization to death.
76. Disinfection and sterilization
are affected by
Initial cleaning of the
device
Physical complexity
of the device
Biofilms and
microbial load
Microbe type and
quantity
HLD exposure time
and concentration
77. When things go wrongWhen things go wrong
Inadequate
cleaning
Using the wrong
disinfectant
Failure to follow
procedures
78. Guideline Excerpts
Infection Risks
“Multiple studies in many
countries have
documented lack of
compliance with
established guidelines for
disinfection and
sterilization.
Failure to comply with
scientifically-based
guidelines has led to
numerous outbreaks.
79. Biofilms interfere in effectiveBiofilms interfere in effective
antimicrobial actionantimicrobial action
“Biofilms are microbial
communities that are
tightly attached to
surfaces and cannot be
easily removed...Bacteria
within biofilms are up to
1,000 times more
resistant to antimicrobials
than are the same
bacteria in suspension
80. Biofilms interfere in effectiveBiofilms interfere in effective
antimicrobial actionantimicrobial action
“One multistate
investigation found that
23.9% of the bacterial
cultures from the internal
channels of 71
gastrointestinal
endoscopes grew
≥100,000 colonies of
bacteria after completion
of all disinfection and
sterilization procedures
81. No Disinfectant is substituteNo Disinfectant is substitute
for the following Proceduresfor the following Procedures
f Hand washing (hand hygiene);
H The use of personal protective equipment
(e.g. gloves) when handling blood, body
substances, excretions and secretions;
s Appropriate handling of patient care
equipment and soiled linen;
e The prevention of needle stick/sharp
injuries;
i Environmental cleaning
E Appropriate handling of waste and
a Taking care of yourself (e.g. immunization)
82. Hand WashingHand Washing
Yet no substitute for washing handsYet 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 beAfter touching anything that might be
contaminatedcontaminated
After handling specimensAfter handling specimens
Before putting on gloves for clinicalBefore putting on gloves for clinical
proceduresprocedures
After removing glovesAfter removing gloves
After using the toilet or latrineAfter using the toilet or latrine
Before leaving workBefore leaving work
84. Created for Dr.T.V.Rao MD’s “e”Created for Dr.T.V.Rao MD’s “e”
learning programmelearning programme
EmailEmail
doctortvrao@gmail.comdoctortvrao@gmail.com
