Hazards of Working with Biological Organisms and

Material

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Reconstructed Spanish flu

Working with Fungi

• Fungi and molds everywhere – Mycosis

• disease caused by infection

– Toxicity• from mycotoxins

– Allergies• airborne spores

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Photo: Adrian J. Hunter

Hazards of Working with Viruses

• Integration of viral genome

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Calculating Risk Level

• Viruses differ in infectiousness

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Hepatitis B virions

Calculating Risk Level

• Different viruses have different consequences– HBV causes Hepatitis

B– HIV causes AIDS

• Treatment or vaccine?

Viruses and Cancer

• Some viruses are oncogenic

• Moderate risk viruses– Include:

papilloma virus, herpes virus, Epstein-Barr virus, and the Hepatitis B and C viruses http://upload.wikimedia.org/wikipedia/commons/c/c4/

Papilloma_Virus_(HPV)_EM.jpg

HPV

Working with Human Blood Products

“Universal Precautions” – Minimizing use of needles and

sharps and proper disposal of these– Wearing PPE– Decontaminating all work surfaces

frequently– Decontaminating waste– Frequent hand washing– Biohazard sign posting

Working with Tissue Culture

• Tissue culture = in vitro propagation of cells taken from tissue of higher organism

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Primary Cell Culture– Newly isolated cells

from tissue or blood– Can be infectious

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Note cells migrating from piece of tissue

Established cell lines

– Many generations in culture– Less likely to pose unknown

threat

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Cultured HeLa cells

Disposal of Biohazardous Waste

Biohazard waste– Discarded cultures of bacteria or cell

culture– Out of date stock cultures– Human and animal waste– Used culture dishes and tubes– Biologically contaminated sharps

Disposal– Place in labeled, closable, leak-proof bags– Place bags in secondary containers to

prevent punctures– Usually decontaminate by autoclaving

Routine Clean-up: Disinfection

• Removal of all or almost all pathogens on a surface

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Disinfectant Characteristics

Chemicals that kill pathogenic microorganisms and other hazardous particles Ideal:– Broad spectrum– Water-soluble– Low toxicity– Inexpensive

No ideal disinfectants

Factors affecting the effectiveness of

disinfectants– Type of organism

• Least resistant: viruses like HIV, Herpes and Hepatitis B

• Then Bacteria• Then Fungi• Then small

viruses like polio and rhinoviruses

• Most resistant are bacterial spores

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Bacterial spore

Disinfectants

• Effectiveness also affected by– Level of contamination– Chemical composition and

concentration of disinfectant– Length of exposure to disinfectant– Texture of surface to be disinfected

Choosing disinfectants• Low—

– gets rid of most bacteria and SOME viruses and fungi

– used for routine clean-up and decontamination

• Intermediate—– gets rid of most bacteria, viruses and fungi– Not spores– includes phenolics and 500 ppm chlorine bleach– used for clean-up of bodily fluids

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http://upload.wikimedia.org/wikipedia/commons/2/24/Red_White_Blood_cells.jpg

Choosing disinfectants

• High—– gets rid of all microorganisms except

large number of bacterial spores– included H2O2 and 1000 ppm chlorine

bleach– used for instruments that can not be

autoclaved

• http://upload.wikimedia.org/wikipedia/commons/1/12/Bacillus_anthracis.png

Bacillus anthracis containing spores (anthrax)

Sanitization• General

reduction of number of microbes on surface– antiseptic

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Sterilization

• Killing of all organisms on a surface

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Autoclave

Biohazard spillsFor personal contamination

– Remove all contaminated clothing and soak lab coats in bleach prior to washing

– Wash skin areas vigorously for at least 10 minutes

– Use an antiseptic if available– Inform supervisor immediately

Biohazard Spills• For a small spill with a

BSL-1 or BSL-2 organism– Wear protective clothing– Soak up spill with

absorbent towels soaked in disinfectant (ie 10% bleach)

– Dispose of towels in biohazard waste

– Clean spill area with fresh towels and disinfectant

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Biohazard spillsFor a BSL-2 organism:

– First evacuate for 10 min. to let aerosols settle

– Cover main spill area with towels soaked in disinfectant. Then flood secondary area with disinfectant.

– Place all waste in biohazard bags.– Put additional disinfectant over

spill area and let sit for at least 20 minutes for decontamination.