This document discusses various methods of chemical sterilization and disinfection. It defines key terms like sterilization, disinfection, antisepsis, and pasteurization. It describes different physical and chemical sterilizing agents such as heat, radiation, ethylene oxide, formaldehyde, and hydrogen peroxide. It classifies disinfectants based on their efficacy as high, intermediate, or low-level and outlines how items are classified based on Spaulding's system. Factors affecting disinfection effectiveness are also discussed.

1. METHODS OF CHEMICAL
DISINFECTION &
STERILISATION
Dr. Dinesh Kr Jain, MD.,
Assistantprofessor,
Department of Microbiology,
SMS Medical college, Jaipur

2. STERILIZATION AND DISINFECTION
Sterilization
• Freeing of an article from all living organism including viable
spores present on the surface of an object or medium. Its an
ideal phenomenon.
• In practice sterilization is a process that kills more than 106
organisms including spores.
Disinfection
• Disinfection is the destruction or removal of all pathogenic
organism or organism capable of giving rise to infection.
Antisepsis
• Reduction or inhibition of microbes found on living tissue.

3. OTHER TERMS
Sanitization
• Lowering of microbial counts to prevent transmission in public setting
like in kitchen of a restaurant.
Degerming
• Mechanical removal of microbes from limited area.
Eg:- Alcohol swab on skin, washing of hands with soap.
Decontamination
• Process of making an article or area free of contaminants including
microbial agents , chemicals and others.
Pasteurization process to kill or markedly reduce the number of
pathogenic and spoilage organisms other than bacterial spores from
milk, wine, or other liquids.

4. Sterility assurance level (SAL)
• probability of a viable microorganism being present on a
product unit after sterilization.
• Usually expressed as 10-6; a SAL of 10-6 means ≤1/1 million
chance that a single viable microorganism is present on a
sterilized item.
• A SAL of 10-6 generally is accepted as appropriate for items
intended to contact compromised tissue (i.e., tissue that has
lost the integrity of the natural body barriers).

5. STERLISATION
• Physical Agents
• Chemical Agents

6. Various Agents in SterlisationPhysical Agents Chemical Agents
Sunlight Alcohols: Ethanol, Isopropyl alcohol
Drying Aldehyde: Formaldehyde,
Glutaraldehyde
Dry heat:
Red heat, Incineration,
Hot air oven
Dyes: Aniline dye, Acridine dye.
Moist Heat:
Autoclaving, Steaming,
Tyndallization, Boiling,
Pasteurization, Vaccine bath,
water bath
Halogens: chlorine, iodine
Filtration :- Air, Liquid Phenolic Compound
Radiation :- Ionizing, Non
ionizing
Gases : Ethylene Oxide, Formaldehyde.
Ultra Sonic Vibration Metallic salts, and surface Active Agents

7. IDEAL DISINFECTANT
• Broad spectrum
• Active In presence of organic matter.
• Effective in both acid and alkaline media
• Fast action
• Highly penetrating
• Stable
• Does Not corrode metals
• Does Not cause local irritation
• Non toxic
• Cheap and safe
Note :- It is only a theoretical concept

8. Spaulding Classification for
disinfectants
• According to their efficiency disinfectant can be classified into
3 categories:
• A) High level disinfectant
• B) Intermediate level disinfectant
• C) Low level disinfectant

9. A) High Level Disinfectant
An agent that kills all microbial pathogens except a small numbers of
spores. It includes-
• Heat sterilization, including steam or hot air.
• Ethylene oxide gas
• Hydrogen peroxide gas plasma
• Glutaraldehyde-based formulations
• Hydrogen peroxide 7.5%
• Per-acetic acid, concentration variable but 0.2% or greater is
sporicidal .
• Ortho-phthalaldehyde (OPA) 0.55%

10. B) Intermediate Level Disinfectant:
• A chemical that kills all microbial pathogens including mycobacteria
and non enveloped viruses except spores.
• Ethyl or isopropyl alcohol (70-90%)
• Sodium hypochlorite (5.25%-6.15% ) provides >100 ppm available
chlorine).
• Phenolic germicidal detergent solution
• Iodophor germicidal detergent solution
C) low level Disinfectant:
Kills only vegetative bacteria, fungi and lipid envelope virus
• Quaternary ammonium germicidal detergent solution

11. • Spaulding also classify the items or equipments used on the
patient. It determines the type of method selected for disinfection
or sterilization.
• According to this items are divided into three categories:
1. Critical items
2. Semi critical items
3. Non critical items

12. Critical Items Semi Critical Items Non Critical Items
Those items which enter
sterile tissues or in the
vascular system.
Those items which come in
contact with mucous membranes
or non intact skin
Those items which
come in contact
with intact skin but
not mucous
membranes
Surgical instruments
Cardiac catheters
Urinary catheters
Implants
Anesthesia equipments
laryngoscope
Endoscopes
Broncoscopes
Cystoscope
Esophageal manometry probes
Anorectal manometry probes
Diaphragm fitting rings
Bed pans
BP cuffs
Bed rails
Bed side tables
Furnitures
Floor
High- level disinfection are
used to treat them
Heat stable items by
Autocalve
Heat sensitive items by
Ethylene oxide or Hydrogen
Peroxide Gas Plasma
high-level disinfection and
intermediate level disinfection are
used for sterilization.
Low level
disinfection are
used to treat them

13. Factors determining effectiveness of disinfection are:
• Number and Location of Microorganisms
• Innate Resistance of Microorganisms
• Concentration and Potency of Disinfectants
• Physical and Chemical Factors i.e pH, temerature etc.
• Organic and Inorganic Matter
• Duration of Exposure
• Biofilms

14. CHEMICAL STERILIZERS
Gaseous sterilizers
1. LTSF
2. Ethylene Oxide
3. Formaldehyde gas
4. Hydrogen peroxide
5. Ozone
6. Beta Propiono Lactone
7. Plasma Technology
Liquid Sterilizers
1. Orthophthaldehyde.
2. Paracetic acid
3. Phenolic compounds
4. Halogens
5. Aldehyde
6. Alcohol
7. Dyes
8. Surface active agents
9. Metallic salts
10. Quaternary ammonium
compounds

15. GASEOUS STERILISERS

16. (1)LTSF - Low Temp Steam Formaldehyde
Overview
• Very low concentration of formaldehyde gas in the presence of
sub atmospheric steam kill the spores due to synergistic action
of steam and formaldehyde gas.
Mode of action
• The introduction of large volume of formaldehyde gas wets the
steam and causes loss of latent heat . This heat causes
denaturation of bacterial proteins.
Use
• For the sterilization of delicate ,heat labile instruments.

17. Advantage
• High efficacy, short handling time, and safety.
Limitations
• Formaldehyde is toxic and irritant to eyes and respiratory tract at
concentration above 2 parts/ million.
Testing of Efficacy
• BIOLOGICAL CONTROL : 106 spores of Bacillus Stearothermophilus
NCTC – 10003 is used.
• Strips must be stored at 40 c for not more than 6 months before
use.

18. Testing of Efficacy of LTSF
Place this spore strips in the chamber of a “ Line and Pickerill Helix”
Operate the cycle and remove the strips aseptically
Now immerse the strips in 15 ml sterile Trypton Soya Broth
Incubate aerobically at 560c for 14 days, shake it daily.
Successful sterilization Unsuccessful sterilization
no turbidity & Turbidity, Sub-culture on NA,
no growth on culture. grey, opaque colonies of
approx. 5mm diameter after
overnight incubation at 560c.

19. (2) ETHYLENE OXIDE (ETO)
Overview
• It is a colourless liquid with a boiling point of 10.70C .
• At normal temperature and pressure it is a highly
penetrating gas with sweet ethereal smell.
• It is highly inflammable and explosive .Explosive tendency
can be eliminated by mixing it with inert gas in 10% conc.
• Kills all microorganism including viruses and spores.

20. EtO sterilization cycle
A typically involves several stages:
• Pre conditions: The product is exposed to a warm, humid
environment for at least 12 hours (70%RH, 55°C)
• Exposure: Vacuum is pulled and EtO gas is introduced. The product is
exposed for 4-8 hours usually. During the process the RH is kept at
approx. 70% and the temperature at 55 °C.
• Post conditions: The EtO gas is removed by repeatedly pulling
a vacuum and then introducing air into the sterilization chamber until
the EtO gas is cleared out (8-12 hours).
It should be noted that there is no standardized cycle for EtO
sterilization.

21. Mode of action
• It acts by alkylating the amino, carboxyl, hydroxyl and sulphydryl
• groups in protein molecule.
• It also reacts with DNA and RNA of microbes.
Use
• For the sterilisation of heat labile delicate instrument.
• In hospitals to sterilise heart valves, respirators, lung machines,
syringes, suture material, dental equipment and linen.

22. Advantage
• ETO penetrates packaging materials and device lumens.
• Single-dose cartridge and negative-pressure chamber minimizes
the potential for gas leak and ETO exposure.
• Equipment is simple to operate and monitor.
• Compatible with most medical materials
Limitations
• ETO is Toxic, Explosive, Inflammable, Mutagenic and Carcinogenic.
• Requires aeration time to remove ETO residue.
• Sterilization chamber is small (∼4–8.8 ft3 ).

23. Test of Efficacy:
BIOLOGICAL CONTROL: 106 spores of Bacillus subtilis subspecies
niger (NCTC 10073,ATCC 9372 )

24. Efficacy testing of ETO
Seal the positive control strips into glass ampoules and include in
test run.
After exposure incubate the test spores in glucose tryptone broth at
pH6.9 and at 250C.
Culture for 14 days for developing turbidity.
Subculture to confirm that the growth consist of the test organism.
In ideal condition there should not be any growth.
Turbidity or any growth on sub culture shows failure of cycle.

25. (3) FORMALDEHYDE GAS
Overview
• This gas is generated by adding 150 gms of KMno4 to
280ml Formalin for every 1000 cu feet of room volume.
• Doors should be sealed and left unopened for 48 hrs.
Mode of Action
• Inactivates proteins by forming covalent cross-links with
several functional groups.

26. Use
• For Fumigation of Operation Theatre and other rooms.
Limitations
• It has pungent smell , irritant to skin , eyes and mucous
membrane.
• Carcinogenic in nature.
• OT has to be closed for at least 24Hrs, so not suitable for EOT’s.
• So Fumigation is obsolete in many developed nations.

27. Overview:
• It has Bactericidal ,Virucidal, Fungicidal, Sporicidal and
Tuberculicidal property.
Mode of action
• It works by producing free hydroxy radicals that can attack
membrane lipids , DNA and other cell components.
(4) Hydrogen Peroxide

28. Uses
• For fumigation of hospital, operation theaters, ICUs,
polyclinics ,dental clinics, OPD, blood banks, laboratories. (in
conc. of 20% v/v)
• For disinfection of surfaces , benches etc. (in conc. of10% v/v)
Advantage
• Short contact period, can be used for EOT fumigation.
Limitations
• The concentrated product may cause skin irritation.
• In case of accidental exposure wash with plenty of water.

30. (5) OZONE
Overview
• Ozone has been used for years as a drinking water disinfectant.
• Ozone is produced when O2 is energized and split into two
monatomic (O1) molecules.
• The monatomic oxygen molecules then collide with O2
molecules to form ozone, which is O3.
• Blue gas with pungent odour.
Mode of action
• It is a potent oxidizing agent.
• This additional oxygen atom makes ozone a powerful oxidant that
destroys microorganisms

31. Use
• A gaseous ozone generator was investigated for
decontamination of rooms used to home patients.
Advantages
• low cost and safe.
• It is highly effective against vegetative bacteria .
• Effective against MRSA, Clostridium difficile and prions.
Limitation
• Toxic
• Corrosive for metal and rubber tubes.
• Limited activity against spores and fungi.

32. Overview
• It is a condensation product of ketone and formaldehyde with
a boiling point of 1630c.
• Rapid biocidal activity.
Limitation
• Not active against spores and prions.
• Less active against viruses.
• Carcinogenic property.
6) BETA PROPIONO LACTONE ( BPL )

33. (7 ) PLASMA TECHNOLOGY
Overview
• Plasma is known as fourth state of matter and consists of ions,
electrons ,or neutral particles.
• Radiofrequency energy is applied to create Electromagnetic
Field.
• Into which Hydrogen Peroxide vapour is introduced which
generates state of plasma containing free radicals of hydrogen
and oxygen.
• The newest version of the unit, which employs a new
vaporization system, has a cycle time from 28-38 minutes.

34. H2O2 LOW TEMP. PLASMA STERILISER

35. Mode of action
•These free radicals i.e. hydroxy and hydroproxyl interact with
essential cell component ( enzyme and nucleic acid) and disrupt the
metabolism of microorganism.
Uses
• Materials and devices that cannot tolerate high temperatures and
humidity, such as some plastics, electrical devices, and corrosion-
susceptible metal alloys, can be sterilized by hydrogen peroxide gas
plasma.
• This method has been compatible with most (>95%) medical
devices and materials tested.

36. Advantage
• The by-products of the cycle (e.g., water vapor, oxygen) are nontoxic
and eliminate the need for aeration. Thus, the sterilized materials can
be handled safely, either for immediate use or storage.
Limitations
• Not effective <420C and inable to process liquids, powder and strong
absorbers (eg. cellulosics)
• The commonest cause of cycle failure is low concentration of
available peroxide vapour.
Test of efficacy
• 106 spores of Bacillus Staereothermophillus and Bacillus subtilis
subspecies Niger.

38. LIQUID STERILISERS

39. (1) ORTHO-PHTH -ALDEHYDE ( OPA)
Overview
• Cleared by FDA in October 1999.
• Contains 0.55% 1,2 benzene di carbox aldehyde.
• OPA solution is a clear, blue liquid with pH 7.5
• High level disinfectant.
Mode of action
• cross linking agent.
• It kills spores by blocking the spore
germination.

40. Uses
• Mycobactericidal and Sporicidal .
• Also effective against glutaraldehyde resistant Mycobacteria.
Advantages
• Stable over a wide pH range, non-irritant to the eyes and nasal
passages and does not require exposure monitoring.
• It has a barely perceptible odor and requires no activation.
• OPA, like glutaraldehyde, has excellent material compatibility.
Limitations
• It stains proteins grey (including unprotected skin) and thus must be
handled with caution.

41. (2) PERACETIC ACID
Overview
• It is active against gram positive and gram-negative bacteria, viruses,
spores, fungi and yeast.
• It is active against all test strains of mycobacteria even in the
presence of organic matter.
• This is used in combination with hydrogen peroxide.
Mode of action
• It denatures the proteins, disrupts the cell wall permeability, oxidizes
sulfur bonds in proteins.
Uses
• Used to prevent biofilm formation.
• Water purification, to sterilize surgical invasive endoscope.
• Used to sterilize automated machine e.g. hemodializers.

42. Advantages
• It lacks harmful decomposition products(i.e., acetic acid,
water, oxygen, hydrogen peroxide).
• Enhances removal of organic material and leaves no residue.
• It remains effective in the presence of organic matter and is
sporicidal even at low temperatures.
Limitations
• Can corrode metallic surfaces.
• Considered unstable, particularly when diluted.

43. 3) PHENOLICS:
Overview
• Introduced by Lister.
• They are useful especially when disinfecting material is
contaminated with organic matter.
• Active against gram positive, gram negative bacteria and
mycobacteria.
Mode of action
• Good protoplasmic poisons.
• Penetrate and disrupts the cell wall and linked with cell proteins.

44. Uses
• Decontamination of infective discharges, bathrooms, bed pans ,
and hospital floors.
• In diluted form it is used as an antiseptic.
Limitations
• Not active against endospores and viruses.
• Phenolics should not be used to clean infant bassinets and
incubators while occupied.(causes hyperbilirubinemia)
• Activity reduced in alkaline pH and hard water.

45. DISINFECTANT OF PHENOLIC GROUP
I. Phenol
II. Chlorophenols
III. Chlorxylenol
IV. Hexa chlorophene
V. Chlorhexidine

46. I. Phenol ( Carbolic Acid )
• Powerful Microbicidal at concentration of 1 %.
• But its activity reduced drastically by dilution.
• At conc. of 0.5 % it is used for sera and vaccines.
Commercial Preparation Of Phenol:
a) Lysol: Liquour Cresolic Saponatus (white fluid less irritant)
b) Sudol: contains xylenols and phenols.
c) Jeyes Fluid: used to treat faeces and sputum before disposal.

48. II. Chloro Phenols
• Non toxic skin antiseptic
• Active against gram positive bacteria
• Commercial preparation: HYCOLIN
• It’s a green fluid containing combination of synthetic phenols.
(including 3:5-dimethyl 4–chlorophenol + 2-benzyl 4-
chlorophenol + 2–hydroxy diphenyl sodium + 3-methyl 4-
chlorophenol + sodium pentachlorophenate)
• It can be incorporated in soap, hand cream or antiseptic lotion
as 1% aqueous solution.

49. HYCOLIN
•Hycolin is a clear green
disinfectant
•used in hospital wards, isolation
wards, operating theatres, post-
mortem rooms, laboratories and
other places where similar
contamination occurs.

50. III. chlorxylenol
• Marketed with a very famous brand
name Dettol
• It contains 4.8 % chlorxylenol used in
the form of soap, cream , fluid.
• It is inactive against pseudomonas
species, infact dettol can be
incorporated in a selective media for
isolation of pseudomonas.

51. IV. Hexa-Chloro Phene
• Active against gram positive organism
• Commercial preparation:-
 Phisohax 3% sol with liquid detergent
 Gamophen In form of soap
 Ster-zac Powder form
Use
Above preparations are important in control of pyogenic cocci in
surgical and neonatal units.

53. V. ChlorHexidine
• Effective against both gram
positive and gram negative
bacteria
• commercial name : HIBITANE
• 0.5-1% solution in 70% isopropyl
alcohol.
• Non toxic skin disinfectant
• Also used as mouth-wash.

54. (4) HALOGENS
• In Halogens Chlorines and Iodines shows bactericidal action.
CHLORINE
• It is bactericidal and has a wide spectrum of action against viruses.
• 3 main chlorine compounds used as disinfectant are:-
1. Bleaching Powder Or Chlorinated Lime
• Contains about 33% of available chlorine.
• Used in the strength of 0.5 to 3%.
2. Hypochlorite
3. Sodum Di-Chloro Iso-Cyanurarate(NADDC)
4. Demand release chlorine dioxide
5. chloramine-T
4,5&6 retain chlorine longer and so exert a more prolonged
bactericidal effect.

55. Mode of action of chlorine The actual microbicidal mechanism of
chlorine is not clear. It might involve a combination of following:-
• Oxidation of sulphydryl enzymes and amino acids
• Ring chlorination of amino acids
• Loss of intracellular contents
• Decreased uptake of nutrients
• Inhibition of protein synthesis
• Decreased oxygen uptake
• Oxidation of respiratory components
• Decreased adenosine tri phosphate production
• Breaks in DNA, and Depressed DNA synthesis

56. SODIUM-HYPOCHLORITE
• Active against gram positive, gram negative bacteria, and
viruses, including HIV and HBV, even in presence of 80% serum.
• Different conc. Of hypochlorites for various purposes
 Virology: 10,000 ppm available cl, 10%.
 Spillage Of Blood: 10,000 ppm of available cl, 10%.
 Discarding Jar: 2500 ppm of available cl, 2.5%.
 Cleaning: 1000 ppm of available cl, 1%.

57. How to prepare working solution of NaOCl
N1×V1= N2×V2
For example-
If 4% NaOCl is given and we have to make 1Ltr of 1% working
solution
4×V1=1×1000;
V1=250ml, i.e. 250ml of 4% NaOCl + 750ml of water= 1Ltr of 1%
NaOCl working solution

58. Limitations:
• Working solution should be prepared daily.
• Less active against mycobacteria.
• Hypochlorite markedly inactivated by organic matter like
cellulose ,cotton, corck and by detergent of opposite polarity.
• Should not be applied to metal, to which it corrodes and to
clothes which may get damaged by it.

59. IODINE
Overview
Active against bacteria, viruses, and fungi.
Preparations of Iodine
Tincture of iodine : It is a weak solution of iodine contain 2.5%
iodine, 2.5% potassium iodide in 90% alcohol.
Iodine: 2% in 70% Isopropyl Alcohol.
Tincture iodine and iodine are used as an antiseptic before surgery
for preparation of skin as they are rapid disinfectant.
• Iodophores: iodine complex with anionic detergent.eg-Povidone-
Iodine(Betadine)i.e. complex of iodine and Polyvinylpyrrolidone
which contains 1% available iodine.

60. Mechanism of action
• disruption of protein and nucleic acid structure and synthesis.
Uses
• Bactericidal antiseptic for intact skin.
• For disinfection of wound.
• It has low sporicidal activity but highly active against
vegetative forms including fungi.
•For disinfecting blood culture bottles and medical equipment,
such as hydrotherapy tanks, thermometers, and endoscopes.

61. (5) ALDEHYDES
Mode of action
• Inactivates bacterial proteins by forming covalent cross links with
several functional groups.
Formalin
• In aqueous solution it is Bactericidal, Virucidal, Sporicidal.
• It is available as 40% w/v solution of it in water containing 10%
Methanol to inhibit polymerization.

62. Formalin
Use
• To preserve Biological Specimen
• To inactivate Viruses and Bacteria in Vaccine.
• Dilution containing 5% Formaldehyde is used as disinfectant directly
to a contaminated surface.
Limitations
• It has pungent strong smell, irritant to eyes and mucous membranes.

63. Gluteraldehyde
Overview
• Less toxic than Formaldehyde.
• Used only on pre-clean surface.
• It has rapid Bactericidal, Virucidal, tuberculicidal action.
• It is active against HIV and HBV even in the presence of 80%
serum.
• For disinfection immersion of contaminated material in ≥2%
gluteraldehyde should be at least 20 min at room temperature.
• Activated solution (by adding alkalinating agents) is sporicidal.
• Activated solutions have a shelf-life of minimally 14 days.

64. GLUTERALDEHYDE
CIDEX :
• 2 % Gluteraldehyde solution supplied together with Alkaline
buffer containing (activator solution) which is added just before
use.
Use:
• Disinfection Of Hospital Equipments:- Endoscope, Cystoscope,
anaesthetic Equipment, Plastic Material And Thermometer.
Advantages
• Relatively inexpensive
• Excellent materials compatibility

65. Limitations
• Respiratory irritation from glutaraldehyde vapour
• Pungent and irritating odour
• Relatively slow mycobactericidal activity
• Coagulates blood and fixes tissue to surfaces
• Allergic contact dermatitis
• Glutaraldehyde vapor monitoring is recommended. The
occupational exposure standard (0.2 ppm for 8 hr weighted
average) must not be exceeded.

66. 6) ALCOHOL
Overview
• Types
1. Ethyl alcohol
2. Isopropyl alcohol
3. Isopropanol: Sterillium
4. Methyl alcohol : rarely use in health care
• They are bactercidal, bacteriostatic, tuberculicidal, virucidal and
fungicidal
Mode of action
• Denaturation Of Proteins.

67. Use
• To disinfect clinical thermometer, scissors, stethoscopes, ultrasound
instruments, hoods.
• used as antiseptic.
Limitations
• Alcohols lacks sporicidal action.
• Can not penetrate protein rich material, not suitable for proper
sterilization.
• They damage the shellac mountings of lensed instruments, tend to
swell and harden rubber and certain plastic tubing after prolonged
and repeated use, bleach rubber and plastic tiles and damage
tonometer tips.

68. (7)DYES
Dyes can be devided in two groups:
A. Aniline Dyes :
• Crystal voilet
• Brilliant Green
• Mallachite green
B. Acridine Dyes
• Proflavin
• Acriflavin
• Euflavin
• Aminacrine

69. (7) DYES
Mode of action
• They impair the DNA complexes of the organism.
Advantage
• Non toxic ,Non irritant.
Use
• Dyes are used as skin and wound antiseptic.
Limitation
• Not Active in presence of organic matter as Pus.
• Not active against Mycobacteria.

70. (8) Metallic Salts And Metallic Organic Compound
Mode of action
They react with sulphydryl groups of protiens
Mercuric chloride:
• Strongly Bacteriosatatic ,weak Bactericidal
Preparation: Thiomersal , Phenyl Mercuric Nitrate
Use : Mild antiseptic
Merthiolate:
• Sod.Methyl Mercury Thio Salicylate, Used in dilution of ( 1 : 10000 )
Use: in preservation of Toxins and Sera, For Inactivation of Vaccines.

71. Copper Sulphate: Used as antifungal
Selenium Compounds: Antifungal
Silver Nitrate: Antibacterial.
• As 1% solution for prophylaxis of Gonococcal Ophthalmia
Neonatarum.
• Silver sulphadiazine in treatment of extensive burn.
• 0.01% silver nitrate solution is used with 11% H2O2 for fogging.

72. (9)Soap And Surface Active Agents
• They disrupt cell membrane.
• They alter the energy relationship at interface producing a reduction
in surface tension.
ANIONIC DETERGENT
SOAPS:
• e.g. Sod.Alkyl Sulphate.
• They contribute in hygiene by mechanical action of hand washing
also.
• Saturated fatty acid soap: active against gram –ve bacteria.
• Unsaturated fatty acid soap: active against gram+ve bacteria.

73. (10)Quaternary Ammonium Compounds
Overview
• Generally fungicidal, bactericidal and virucidal against lipophilic
(enveloped) viruses.
• They are not sporicidal and generally not tuberculocidal.
• Non toxic.
• Commonly used compounds: Alkyl dimethyl benzyl ammonium
chloride, Alkyl didecyl dimethyl ammonium chloride and dialkyl
dimethyl ammonium chloride.
Mechanism of action
• inactivation of energy-producing enzymes, denaturation of essential
cell proteins, and disruption of the cell membrane.

74. Commercial preparation: D-125
• D-125 is effective against more 141 micro-organisms like HIV,
HBV, HCV, Polio, H5N1, Delhi Super Bug etc.
Contents-
Alkyl Dimethyl Benzyl Ammonium Chloride-2.37%,
Alkyl Dimethyl Ethylbenzyl Ammonium Chloride2.37%
Inert Ingredients-95.26%
Direction for use-
Dilution Critical Area 1:64 (15 ml in 1 litre of water )
Dilution Non-Critical Area 1:128 (7.5 ml in 1 litre of water )

75. Use
• Surface and Environment disinfectant(Fogging of OT)
• Discarding jars
• Instrument sterilization
• Terminal disinfection of infectious waste
• disinfecting medical equipment that contacts intact skin (e.g., blood
pressure cuffs).
Limitations:
• Inactivated by organic matter.
• Pus forming bacteria Pseudomonas pyocyanea is resistant to it.
• Inactive against mycobacteria and enveloped viruses.

76. Hand Antiseptic / Hand Sanitiser
• Hand sanitizer is a supplement or alternative to hand
washing with soap and water.
Many preparations are available, including gel, foam, and
liquid
solutions.
Alcohlic Hand Sanitiser contains
• Isopropanolol /Isopropyl alcohol
• Ethanol
• N-propanolol
Non alcohlic hand sanitiser contains
• Benzalkonium chloride
• Povidone –iodine
• Triclosan
Sterillium
contains
Isopropanol
N-propanol

77. Testing Of Disinfectants
1. Rideal-Walker test-
• Suspension containing equal No. of typhoid bacilIi are submitted to
action of varying concentration of phenol and of disinfectants to be
tested
• Dilution of test disinfectant divided by corresponding dilution of
Phenol stated as Phenol Coefficient.
2. Chick Martin Test:-
• Modification of Rideal-Walker test.
• Disinfectant act in presence of organic matter.
NOTE: But both of these tests are irrelevant and inappropriate.

78. 3. KELSEY SYKES Capacity Test:
Efficiency is judged in terms of its ability to inactivate a known no. of
std strain of a staphylococcus on a given surface in certain time.
4. In-Use Test
With the help of sterile pipette transfer 1ml of used disinfectant into
9ml of nutrient broth in a sterile container.
• Place 0.02 ml drops of this mixture on to 10 different areas of dried
nutrient agar plates.
• Incubate one plate for 3 days at 370c and other for 7 days at room
temp
• If growth Is present in more than 5 Drops on either plate, it shows
failure of disinfection.

79. Disinfection Of Surfaces And Spillages
• HYPOCHLORITE in concentration of 10,000 ppm of available cl for 30
mins.
• Cover the spillage with with disposable paper soaked in Disinfectant.
left for 10 mins
• Collect it into a infected waste container with disposable gloves
• The area should be swabbed with fresh Disinfectant.
• Note : In case of large spillage a Germicidal Powder e.g. PRESEPT
granules (SURGIKOS) can be used.

80. Newer concepts for OT sterilisation
• Hydrogen peroxide, hydrogen peroxide with silver nitrate,
peracitic acid, D-125 and other chemical compounds of
formaldehyde should be used in place of the currently prevalent
practice of using formaldehyde.
• These agents are dispersed with the aid of a fogger-like device
inside the theatre environment.
• The contact time is about an hour and the theatre can be used
immediately after the contact time.

81. Emerging Compounds in use for Sterilization of
Operation theatres:
Bacillocidrasant:
• A newer and effective compound in environmental decontamination
with very good cost/benefit ratio, good material compatibility,
excellent cleaning properties and virtually no residues.
Advantages
• Low concentration is used
• Provides complete asepsis within 30 to 60 minutes.
• Cleaning with detergent or carbolic acid not required.
• Formalin fumigation not required.
• Shutdown of O.T. for 24 hrs. not required.

82. VIRKON
• safe virucidal, bactericidal, fungicidal, mycobactericidal and
non-toxic compound.
• contains oxone (potassium peroxymonosulphate), sodium
dodecylbenzenesulfonate, sulphamic acid; and inorganic
buffers.
• It is typically used for cleaning up hazardous spills, disinfecting
surfaces and soaking equipment.

83. Thank you.