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Disinfection and Sterilization in Health care
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DISINFECTION AND STERILIZATION IN HEALTH CARE
Dr.T.V.Rao MD
A Tribute to Ignaz Semmelweiss (1818-1865)
Ignaz Semmelweiss (1818-
1865)
• Established that high maternal mortality was due to failure of doctors to wash hands after post-mortems
• Reduced maternal mortality by 90% Dr.T.V.Rao MD' TMC Kollam Kerala 2
What is Disinfection
• Disinfection may be defined as: Cleaning an article of some or all of the pathogenic organisms which may cause infection
• Perfect disinfectant would also offer complete and full sterilization, without harming other forms of life, be inexpensive, and non-corrosive. Most disinfectants are also, by their very nature, potentially harmful (even toxic) to humans or animals.
Dr.T.V.Rao MD 3
What is the Best Choice in Disinfection Practices
The Ideal Disinfectant
Resistant to inactivation
Broadly active (killing pathogens)
Not poisonous (or otherwise harmful)
Penetrating (to pathogens)
Not damaging to non-living materials
Stable
Easy to work with
Otherwise not unpleasant Dr.T.V.Rao MD 5
Terminology
• Antisepsis: chemical destruction of vegetative pathogens on living tissue
• Degerming: mechanical removal of microbes from limited area
• Sanitization: lowering microbial counts on eating and drinking utensils to safe levels
Dr.T.V.Rao MD 6
Terminology • Biocide or germicide: kills
microorganisms
• Fungicide: kills fungi
• Virocide: inactivates viruses
• Bacteriostatic agent: stops growth of bacteria Dr.T.V.Rao MD 7
Antiseptics versus Disinfectants
Antiseptics: 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
High-level versus low-level disinfectants
Dr.T.V.Rao MD 8
Beginning of Scientific era of sterilization and Disinfection
Dr.T.V.Rao MD 9
Disinfection x Sterilization
• Sterilization is absolute, removes microbes and spores too.
• To achieve Sterilization is Expensive, not sustainable, many times not needed.
• An effective Disinfection reduces the infections drastically.
Dr.T.V.Rao MD 10
• Process of destroying all microbial forms. A sterile object is one free of all microbial forms, including bacterial spores.
• More thorough than disinfection
Sterilization
Dr.T.V.Rao MD 11
• Process of reducing or eliminating living pathogenic microorganisms in or on materials, so they are no longer a health hazard.
For example: use of alcohol before drug injection.
Disinfection
Dr.T.V.Rao MD 12
Soaps are
sodium or
potassium salts
of fatty acids, a
natural product
Detergents,
instead, are
artificial
surfactants
Soap and detergents
Dr.T.V.Rao MD 13
Halogens Halogens are the seventh (VII) column of the periodic table of
elements
Two halogens are regularly employed as antimicrobials: Iodine
and Chloride
Iodine: commonly used as an antiseptic against all microbes,
fungi, and viruses
Iodine: It inhibits protein synthesis and oxidizes –SH groups of
amino acids
Chlorine: Used as a disinfectant (10% bleach)
Chlorine: Hypochlorous acid (HOCl) is a product, formed in water,
that is the active form of the disinfectant
Chlorine: Applied in treatment of drinking water, swimming pool,
and sewage
Dr.T.V.Rao MD 14
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.
Dr.T.V.Rao MD 15
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.
Dr.T.V.Rao MD 16
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.
Dr.T.V.Rao MD 17
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
Dr.T.V.Rao MD 18
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.
Dr.T.V.Rao MD 19
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.
Dr.T.V.Rao MD 20
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
Dr.T.V.Rao MD 21
Gaining importance in Hand Washing 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
Dr.T.V.Rao MD 22
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
Dr.T.V.Rao MD 23
Hypochlorite's • Other disadvantages of
hypochlorite's 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.
Dr.T.V.Rao MD 24
Hypochlorite's • Hypochlorite's 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.
Dr.T.V.Rao MD 25
Hypochlorite's Most recommended in
• They are included in most recommendation for decontamination of hepatitis and AIDS viruses
Dr.T.V.Rao MD 26
Hypochlorite's
• Chlorinated drinking water should not exceed 6 to 10 ppm of free chlorine with the lower value being in continuous flow or low volume reservoir systems.
Dr.T.V.Rao MD 27
HIGH LEVEL DISINFECTANTS
Dr.T.V.Rao MD 28
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.
Dr.T.V.Rao MD 29
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 Dr.T.V.Rao MD 30
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.
Dr.T.V.Rao MD 31
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 Dr.T.V.Rao MD 32
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
Dr.T.V.Rao MD 33
Glutaraldehyde
• 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.
Dr.T.V.Rao MD 34
Ethylene oxide
Dr.T.V.Rao MD 35
• Ethylene oxide, also called oxirane, is the organic compound with the formula C2H4O. It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape (circular). This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered ring consisting of two carbon and one oxygen atom.
• Highly effective against most microbes
• Highly diffusive
• Compatible with a wide variety of materials in devices and packaging
Ethylene oxide ADVANTAGES
• Complex process
• Longer turn-around times
– BI Testing
– Residual dissipation
• Safety concerns
– Flammable
– Explosive
• OSHA concerns
– Carcinogen
• EPA concerns
– Emissions
Ethylene oxide DISADVANTAGES
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
Dr.T.V.Rao MD 38
• Per acetic, or peroxyacetic, acid is characterized by a very rapid action against all microorganisms. A special advantage of per acetic 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
Per acetic Acid
Dr.T.V.Rao MD 39
Per acetic Acid and Hydrogen Peroxide
• Two chemical sterilants are available that contain per acetic acid plus hydrogen peroxide (0.08 per acetic acid plus 1.0% hydrogen peroxide [no longer marketed], 0.23% per acetic acid plus 7.35% hydrogen peroxide). The bactericidal properties of per acetic acid and hydrogen peroxide have been established.
Dr.T.V.Rao MD 40
Per acetic acid and hydrogen peroxide
useful in Hem dialyzers
• 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.
Dr.T.V.Rao MD 41
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 microbicidal because these materials absorb the active ingredients. As with several other disinfectants (e.g., phenolic, Iodophor) gram-negative bacteria have been found to survive or grow in these preparations
Dr.T.V.Rao MD 42
Dr.T.V.Rao MD 43
Which Skin Preparation Agent is Superior
• Researchers conducted a review of surgical skin prep agents to conclude which agent was most cost-effective and superior in preventing surgical site infections. Based on information collected from two databases, researchers compared povidone-iodine, Chlorhexidine gluconate, parachoroxylenol and iodine povacrylex (0.7 percent available iodine) in 74 percent isopropyl alcohol (DuraPrep). Researchers concluded that each prep agent has specific advantages and disadvantages and no one skin prep agent is superior in all clinical situations. Factors to consider when choosing a skin prep agent include surgeon preference and environmental risks.
Fumigation a biohazard procedure ?
Dr.T.V.Rao MD 44
What Is Formaldehyde?
Dr.T.V.Rao MD 45
• Formaldehyde has the chemical elements carbon, hydrogen and oxygen in its structure. Hydrocarbons are among the most common of chemical compositions. Formaldehyde is usually sold as an aqueous or watery solution called formalin, which contains 37 to 50 percent formaldehyde by weight. It is soluble in water, but not in most organic solvents, except alcohol and ether.
Fumigation
• To sterilize the operation theatre formaldehyde gas (bactericidal & sporicidal,viricidal) is widely employed as it is cheaper for sterilization of huge areas like operation theatres. Formaldehyde kills the microbes by alkylating the amino acids and sulfydral group of proteins and purine bases.
• In spite of the gas being hazardous continues to be used in several developing countreis
Dr.T.V.Rao MD 46
Procedure of Fumigation
• Thoroughly clean windows, doors, floor, walls and all washable equipment's with soap and water.
• Close windows and ventilators tightly. If any openings found seal it with cellophane tape or other material.
• Switch off all lights, A/C and other electrical & electronic items
• Calculate the room size in cubic feet (L×B×H) and calculate the required amount of formaldehyde as given in Dr.T.V.Rao MD 47
Personal care during fumigation
• Adequate care must be taken by wearing cap, mask, foot cover, spectacle .,
• Formaldehyde is irritant to eye & nose; and it has been recognized as a potential carcinogen.
• So the fumigating employee must be provided with the personal protective equipment's.
Dr.T.V.Rao MD 48
Creating the Formaldehyde gas
• Electric Boiler Fumigation Method: For Each 1000 cu.ft of the volume of the operation theatre 500ml of formaldehyde (40% solution) added in 1000ml of water in an electric boiler. Switch on the boiler, leave the room and seal the door. After 45 minutes (variable depending to volume present in the boils apparatus) switch off the boiler without entering in to the room .
Dr.T.V.Rao MD 49
Methods on Fumigation
• In principle we have to generate Formaldehyde gas.
• Can be done by
Most easier way to mix the needed quantity of Formalin to water and heating at lower temperatures at 800c – 900c
Can done also with addition of Formalin to potassium permanganate
Dr.T.V.Rao MD 50
Adding Potassium Permanganate to formaldehyde..
• Potassium Permanganate Method: For every 1000 cubic feet add 450gm of Potassium permanganate (KMnO4) to 500 ml of formaldehyde (40% solution). Take about 5 to 8 bowels (heat resistant; place it in various locations) with equally divided parts of formaldehyde and add equally divided KMnO4 to each bowel. This will cause auto boiling and generate fume.
• After the initiation of formaldehyde vapour, immediately leave the room and seal it for at least 48 hours.
Dr.T.V.Rao MD 51
Fumigation to be neutralized
• Neutralize Residual formalin gas with Ammonia by exposing 250 ml of Ammonia per liter of Formaldehyde used.
• Place the ammonia solution in the centre of the room and leave it for 3 hours to neutralize the formalin vapour
Dr.T.V.Rao MD 52
An example is set as..
• Operation Theatre Volume = L×B×H = 20 × 15 × 10 = 3000 cubic feet
• Formaldehyde required for fumigation = 500 ml for 1000 cubic feet
• = So 1500 ml of formaldehyde required
• Ammonia required for neutralization = 150ml of 10% ammonia for 500 ml of formaldehyde
• = So 450 ml of 10% ammonia require
Dr.T.V.Rao MD 53
Need for Newer Chemical Agents in Hospital Use
• 1. A need for Non Aldehyde based Chemicals is growing concern
• 2 Need for quicker sterilization methods with ever increasing work loads.
• 3. Need for non toxic safe agents.
Dr.T.V.Rao MD 54
Bacillocid® rasant
• Formaldehyde-free disinfectant cleaner with low use concentration
• very good cost/benefit ratio
• good material compatibility
• excellent cleaning properties
• virtually no residue
Dr.T.V.Rao MD 55
Bacillocid® rasant
• Active ingredients: Glutaral 100 mg/g, benzyl-C12-18-alkyldimethylammonium chlorides 60 mg/g, didecyl-dimethylammonium chloride 60 mg/g.
• Bacillocid® rasant is suitable for the disinfectant cleaning of washable surfaces using the wet-wipe-procedure.
• Especially suitable for economic short-term disinfection in risk areas that are likely sources of infection
Dr.T.V.Rao MD 56
Newer and Non Toxic compounds.
• A Chemical compound VIRKON gaining importance as non Aldehyde compound.
• Virkon proved to be safe Virucidal
Bactericidal,
Fungicidal
Mycobactericidal
Dr.T.V.Rao MD 57
VIKRON is Finding Place in
• As a Chemical disinfectant.
• Disinfects Medical devices.
• Disinfects Laboratory equipment.
• Decontaminate spillages with Blood and body fluids.
• Finding usefulness in replacing autoclaving and saving time.
Dr.T.V.Rao MD 58
Yet no Ideal Chemical Agent
• Researchers concluded that each prep agent has specific advantages and disadvantages and no one skin prep agent is superior in all clinical situations. Factors to consider when choosing a skin prep agent include surgeon preference and environmental risks.
Dr.T.V.Rao MD' TMC Kollam Kerala 59
Gas plasma Sterilization
Dr.T.V.Rao MD 60
• Plasma is a fourth state of matter which is distinguishable from liquid, solid, or gas. In nature, plasma is widespread in outer space.
• Gas plasma generated in an enclosed chamber under deep vacuum using Radio frequency or Microwave emery to excite gas molecules are produced charged particles
• Can be used for hand sterilization
What is Gas Plasma
Dr.T.V.Rao MD 61
How Gas Plasma works.
• Many particles are in the form of free radicals
• A free radical is an Atom with an unpaired electron and is a highly reactive species
• The mechanism of action of this device is the production of free radicals within a plasma field that are capable of interacting with essential cell components, ie is enzymes and nucleic acids. And thereby disrupt the metabolism of microorganisms.
Dr.T.V.Rao MD 62
Gas Plasma - Sterilization
• Plasma sterilization operates differently because of its specific active agents, which are ultraviolet (UV) photons and radicals (atoms or assembly of atoms with unpaired electrons, therefore chemically reactive, e.g., O and OH, respectively
Dr.T.V.Rao MD 63
• Destruction by UV irradiation of the genetic material of the microorganism; this is a statistical process requiring a sufficient number of lesions of the DNA strands.
• Erosion of the microorganism, atom by atom, through intrinsic photo desorption
BASIC MECHANISMS OF PLASMA STERILIZATION
Dr.T.V.Rao MD 64
Hydrogen Peroxide Sterilization Offers Fast
Cycle Times • Benefits of gas
plasma (vaporized hydrogen peroxide) sterilization are fast cycle times, the absence of toxic residuals, and a low-moisture environment not exceeding 50ºC,
Dr.T.V.Rao MD 65
Waste disposal • Clinical waste - HIGH risk
–potentially/actually contaminated waste including body fluids and human tissue
–yellow plastic sack, tied prior to incineration
• Household waste - LOW risk
–paper towels, packaging, dead flowers, other waste which is not dangerously contaminated
– black plastic sack, tied prior to incineration
Dr.T.V.Rao MD' TMC Kollam Kerala 66
New CDC guidelines
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.
Dr.T.V.Rao MD 67
Han
Yet – No substitute for Hand Washing :
Immediately on arrival at work Before and after examining each client After touching anything that might be
contaminated After handling specimens Before putting on gloves for clinical procedures After removing gloves After using the toilet or latrine Before leaving work
Dr.T.V.Rao MD 68
Hand Hygiene Compliance
• Researchers have implemented a hand hygiene program driven by a behavioral change approach to increase hand hygiene compliance.. It included access to alcohol sanitizer, education as well as ongoing audit and feedback.
Dr.T.V.Rao MD' TMC Kollam Kerala 69
Hand Hygiene Techniques Many Ways
1. Alcohol hand rub
2. Routine hand wash 10-15 seconds
3. Aseptic procedures 1 minute
4. Surgical wash 3-5 minutes
Dr.T.V.Rao MD' TMC Kollam Kerala 70
Remember we are More important than many Chemicals
Dr.T.V.Rao MD 71
Soap Water and Common sense are Best
Antiseptics- William Osler
Dr.T.V.Rao MD' TMC Kollam Kerala 72
• Programme created by Dr.T.V.Rao MD for Health Care Workers in
Developing World
