Lecture 7 decontamination of infectious material and disposal of laboratory waste copy

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Decontamination of infectiousmaterial and disposal of

laboratory wasteDr. Hafez Alsumairy

Diagnostic & Molecular Microbiology2014-2015

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Responsibility of the laboratory for safedecontamination, recycling, and disposal• Risks can be minimized by laboratory staff:

• Practicing personal hygiene,• Following safe working practices,• Knowing and following correct methods for:

• Separating infectious materials and laboratory waste,• Decontaminating and disposing of non-reusable infectious

waste,• Making non-infectious, cleaning, and sterilizing reusable

articles.

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Factors that influence the degree of killing• Types of organisms• Number of organisms• Concentration of disinfecting agent• Presence of organic material (e.g.,

serum, blood)• Nature of surface to be disinfected• Contact time• Temperature• pH• Biofilms• Compatibility of disinfectants and

sterilants

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Methods of decontamination and disposalof laboratory wasteMethods of decontamination:1. Autoclaving (sterilization)2. Boiling (effective method of disinfection)3. Use of chemical disinfectantsDisinfection• This aims to destroy or at least reduce the number of contaminating

microorganisms to levels that are no longer regarded as harmful to health.• Sterilization

• This is the most reliable way of achieving decontamination because it completely destroysmicroorganisms, including bacterial spores.

• A temperature of 121°C and holding time of 15 minutes, timed from when 121°C• Prions, require autoclaving at 134°C for 18 minutes to be inactivated

• Boiling

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Methods of decontamination and disposalof laboratory wasteMethods of disposing:1. Incineration

• Destruction by burning2. Burial in a deep covered waste

pit or landfill• Deep (4–5 metres) and wide

(1–2 metres)

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Chemical disinfectants

1. Phenolics• Active against all non-sporing bacteria including mycobacteria

2. Chlorine-releasing products3. Peroxygen compounds4. Alcohols

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Chemical disinfectants

Phenolics• Dettol is in fact 4-chloro-3,5-dimethylphenol• Active against all non-sporing bacteria including mycobacteria• Phenolics are not markedly inactivated by proteins.• Activity is reduced At an alkaline pH• At 2–5% v/v not be kept for more than 24 hours• Non-corrosive• Used for wiping bench surfaces and floors

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Chemical disinfectants

Chlorine-releasing disinfectants• Gram positive and Gram negative bacteria and viruses• Sodium hypochlorite solutions (Chloros) 5% available chlorine• Calcium hypochlorite granules or tablets (70% available chlorine)• Sodium dichloroisocyanurate (NaDCC)

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Chemical disinfectantsPeroxygen compoundsAlcohols• Ethanol and propanol at 70–80% v/v• Disinfecting skin and surfaces• Penetration of organic matter is poor• Highly active against mycobacteria, non-sporing Gram positive and Gram negative

bacteria, fungi, and enveloped virusesAldehydes• Formaldehyde5%• Glutaraldehyde (glutaral) 2%• Toxic, irritant, and mutagenic

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Disinfection

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Waste disposal

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Waste disposal

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Waste disposal

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Waste disposal

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Sterilization

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Thank you

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