Disinfection and Sterilization in Health care

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

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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

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Beginning of Scientific era of sterilization and Disinfection

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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.

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• Process of destroying all microbial forms. A sterile object is one free of all microbial forms, including bacterial spores.

• More thorough than disinfection

Sterilization

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• 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

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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

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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.

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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.

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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.

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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

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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.

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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.

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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

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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

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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

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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.

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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.

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Hypochlorite's Most recommended in

• They are included in most recommendation for decontamination of hepatitis and AIDS viruses

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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.

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HIGH LEVEL DISINFECTANTS

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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.

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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.

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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

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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.

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Ethylene oxide

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• 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

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• 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

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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

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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 ?

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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

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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.

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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 .

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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.

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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

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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

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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.

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Bacillocid® rasant

• Formaldehyde-free disinfectant cleaner with low use concentration

• very good cost/benefit ratio

• good material compatibility

• excellent cleaning properties

• virtually no residue

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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

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Newer and Non Toxic compounds.

• A Chemical compound VIRKON gaining importance as non Aldehyde compound.

• Virkon proved to be safe Virucidal

Bactericidal,

Fungicidal

Mycobactericidal

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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.

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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

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• 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

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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.

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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

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• 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

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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,

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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.

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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

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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

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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

• Email

• doctortvrao@gmail.com