11. decon draft

8/11/2019 11. Decon Draft

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Risk Management Serv ices

www.riskmanagement.ubc.ca


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Decontamination and SterilizationMethods

Laboratory Biological Safety


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Definitions

Sterilization:any process, physical or chemical, which resultsin the absence of all life on or in an object. This term appliesespecially to the destruction of microorganisms, including

bacteria, fungi, and their spores, and the inactivation of viruses

Decontamination:to destroy, remove, or neutralize livingorganisms, toxic agents or chemical carcinogens on a surface or

object (this does not imply either total destruction or totalremoval); to make an object safe for unprotected individuals


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Disinfection:to use a chemical agent to kill or inactivate mostvegetative bacteria, fungi, and viruses but not necessarilyspores. This term applies to a chemical used on inanimate

surfaces not to living tissues

Germicide: a substance used to destroy a specificmicroorganism

Algicidean agent that kills algae

Bacteriocide- an agent that kills vegetative bacteria andpossibly some less resistant spores (commercial term)

Fungicidean agent that kills fungi

Sporicidean agent that kills spores

Virucidean agent that inactivates, destroys or kills viruses

Tuberculocidean agent that kills mycobacteria

Definitions


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General Precautions

All areas where infectious materials have been handled need tobe decontaminated a minimum of daily. Ideally an area will bedecontaminated before and after work is performed

All infectious materials and/or contaminated equipment orapparatus should be decontaminated before being washed,removed, stored, or discarded

All biohazardous materials should be placed in an appropriately

marked refrigerator, waste or incubator, sterilized or otherwiseconfined at the end of each work day

Do not store materials in the autoclave!


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General Precautions

Dry hypochlorites, or any otherstrong oxidizing material, MUSTNOTbe autoclaved with organicmaterials such as paper, cloth, oroils

If organic material in the autoclavecatches fire, the oxidizer will

stimulate the fire and may cause anexplosion because of the highpressure in the autoclave


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Lab Benches

GOOD

B D


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Examples of Biological Waste

Waste Type Examples

Microbiology laboratory

(Biohazardous)

laboratory cultures, stocks of specimens of micro-

organisms, live or attenuated vaccines, human or

animal cell cultures used in research, and laboratory

material that has come into contact with any of the

above

Animal animal tissues, organs, body parts, carcasses,

bedding, animal blood and blood products

Human anatomical human tissue, organs, body parts

Human blood and blood

products

human fluid blood/blood products, items saturated or

dripping with blood, body fluids contaminated with

human blood, human body fluids removed for

diagnosis or during surgery, treatment or autopsy

Clinical & laboratory

waste sharps

needles, syringes, blades or laboratory glass capable

of causing punctures/cuts

defined as per BC Hazardous Waste Regulation
http://www.bclaws.ca/EPLibraries/bclaws_new/document/LOC/freeside/--%20E%20--/Environmental%20Management%20Act%20SBC%202003%20c.%2053/05_Regulations/27_63_88%20Hazardous%20Waste%20Regulation/63_88_01.xml#section1http://www.bclaws.ca/EPLibraries/bclaws_new/document/LOC/freeside/--%20E%20--/Environmental%20Management%20Act%20SBC%202003%20c.%2053/05_Regulations/27_63_88%20Hazardous%20Waste%20Regulation/63_88_01.xml#section1


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Biological Waste Minimization Measures

SEGREGATE uncontaminatedsolid waste from biomedical andbiohazardous waste (all risk groups)

Use products with less environmental impact:

Petri dishes with 35% less plastic

Glassware that can be decontaminated and reused

Refillable pipette racks Other reusable or recyclable products


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Methods of Decontamination

Heat or autoclaving

Autoclaving is the most dependable procedure for ensuring thecomplete destruction of microorganisms. It generally involvesheating in a chamber employing saturated steam under a relativepressure of 103 kPa (15 psi) to achieve a chamber temperature ofat least 121OC for a minimum of 60 minutes

Chemical decontaminants

Chemical decontaminants are toxic chemicals that can kill certaintypes of microorganisms

Radiation

This method is not used in academic laboratories


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Sterilization by Heat

Moist Heat Dry Heat

Temperature Time Temperature Time

100 oC 20 hours 120 oC 8 hours

110 oC 2.5 hours 140 oC 2.5 hours

115 oC 50 minutes 160 oC 1 hour

121 oC 15 minutes 170 oC 40 minutes

125 oC 6.5 minutes 180 oC 20 minutes

The following table demonstrates the heat equivalency betweenMoist and Dry Heat


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Autoclave

When autoclaving, the materials beingsterilized must come into contact with steamand heat for actual sterilization to result. It isfor this reason that the use of some form of

efficacy indicator must be done with each cycle

Sterilization Indicators: Routine Testing

Autoclave Tape

Autoclave Charts

Chemical

Biological


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This protocol describes the autoclavetreatment conditions and requirements for

laboratory solid waste contaminated with RiskGroup 1 and 2 Biohazardous Materials(Category B Infectious Substances), inLaboratories in UBC Point Grey Campus.

This treatment will allow the safemanagement of the resulting waste as non-hazardous solid waste in accordance with thewaste delisting approved by the Ministry ofEnvironment.

The new procedure can be found herealongwith the training videos.

New Disposal Procedure: Solid Waste

Contaminated with Microbiological Risk Group 1and Risk Group 2 Agents
http://riskmanagement.ubc.ca/environment/hazardous-waste-management/new-disposal-procedures-risk-groups-1-2http://riskmanagement.ubc.ca/environment/hazardous-waste-management/new-disposal-procedures-risk-groups-1-2


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Resistance to Chemical Decontaminants

Bacterial Spores

Bacillus subtilis, Clostridium sporogenes

MycobacteriumMycobacterium tuberculosis

Nonlipid or Small VirusesPoliovirus, Coxsackievirus, Rhinovirus

FungiTrichophyton sp., Cryptococcus sp., Candida sp.

Microorganisms can be more or less resistant to decontaminationand the general order is (most to least resistant):


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Resistance to Chemical Decontaminants

FungiTrichophyton sp., Cryptococcus sp., Candida sp.

Vegetative BacteriaPseudomonas aeruginosa, Staphylococcus aureus, Salmonella

choleraesuis

Lipid or Medium-Size VirusesHerpes simplex virus, Cytomegalovirus, Respiratory syncytial virus,

Hepatitis B virus, Human Immunodeficiency virus


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Microorganisms are affected by chemical decontaminantsthrough:

Cell lysis

Protein coagulation or denaturation Enzyme denaturation or inactivation

Destruction of enzyme substrates

Chemical Decontaminants


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Decontaminant Effectiveness

The effectiveness of a decontaminant is

influenced by a number of factors:

Organic Load Surface Topography

Method of Application

Concentration

Contact Time

Temperature Relative Humidity

pH and Stability


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The ideal decontaminant would be a broad spectrum agent able toact effectively against all biohazards. It would be fast acting, noteasily inactivated, non-toxic to the user, non-corrosive,economical, easy to use, easy to dispose of and have a long "uselife". Unfortunately, there is no one chemical agent that canfulfill all of these requirements

There are several categories of liquid decontaminants, each of

which has different characteristics and different ranges ofusefulness. Some agents are not compatible, so always follow themanufacturers instructions regarding mixing agents, dilution,storage and use of the decontaminant

Types of Chemical Decontaminants


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Liquid Decontaminants

Alcohols

Ethyl or isopropyl alcohol in a concentration of 70 - 85%by volume is often used

Pros:easy to use and non corrosive Cons:extremely flammable, evaporates easily, inactivated

by organic matter, and no cleansing properties

Effective:lipid-containing viruses, enveloped viruses, andvegetative bacteria. Longer contact times are needed for

fungi and some mycobacteria Ineffective:non-enveloped viruses and bacterial spores


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Chlorine Compounds

This halogen is a universal decontaminant active againstall microorganisms including bacterial spores. Chlorinecombines with protein and rapidly decreases inconcentration in its presence. It is a strong oxidizingagent

Pros:inexpensive, readily available, and broad spectrum

Cons:corrosive, short use life, and inactivated by

organic material Effective:everything

Ineffective:14C (produces radioactive CO2) should notbe used with any radioisotope where the reaction wouldcreate a volatile compound

Examples:Bleach, Javex, Presept, Alcide



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Formaldehydes

Formaldehyde for use as a decontaminant is usuallymarketed at about 37% concentration of the gas in watersolution (referred to as formalin), or as a polymerizedcompound called paraformaldehyde. Formaldehyde, in aconcentration of 5% active ingredient (18.5 g/lformaldehyde), is an effective liquid decontaminant

Pros:broad spectrum and less susceptible to inactivationby organic material

Cons:long contact times (30+ minutes), loss of activityat cooler temperatures, pungent odour, expensive, andshort use life

Effective:everything

Examples:Cidex 7, Sporocidin, and Sonacide



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Gas Decontaminants

Formaldehydes

The chemical of choice for space decontamination

Used at a concentration of 10,000 ppm (TLV 0.3 ppm with

a ceiling of 0.5 ppm) It has limited penetrating abilities

It is a suspected carcinogen

It is a sensitizer


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Radiation Decontaminants

Ionizing Radiation Ionizing radiation will destroy all microorganisms Gamma radiation - either Co-60 or Cs-137

None of these methods are presently used at UBC. The risk fromthe radiation outweighs the decontamination benefits

Nonionizing Radiation Ultraviolet radiation the short wavelengths of light beyond the

violet end of the visible spectrum

Produces thymine dimers in cells which leads to the death of themicroorganism

A narrow range of the UV spectrum has antimicrobial activity butis limited by poor penetrating power

May not lead to total decontamination of the area UV lights need to be changed every 3-6 months to be effective


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Most chemicals are whitepowders, so if you dont cleanup after yourself no one willknow what the white powder

left behind is

Clean-up


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Clean-up

All spaces where biological work isperformed need to bedecontaminated at least once daily

Not only is this space messy, thereis also a very large possibility ofcontamination and makesreproducible data difficult to obtain


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Decontamination and Sterilization are notequivalent.

There are several methods of decontamination, each with

advantages and dis-advantages: Heat/autoclaving,

Chemical decontaminants

Radiation

It is the responsibility of the supervisor to ensure that workersare appropriately trained on how to clean up a biological spillfor their specific projects.

The next module will discuss Lab Emergency Procedures

Summary


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11. decon draft

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