Definition of Terms,

STERILIZATION

destruction of all forms of life including bacterial spores

AUTOCLAVE

pressure saturated steam at 121ᵒC for 15-20 mins

121ᵒC ; 15-20 mins

AUTOCLAVE

• pressure saturated steam at _____ for ____

DISINFECTANT

Is a chemical or physical agent that is applied to inanimate objects to kill microbes

ANTISEPTIC

A chemical agent that is applied to living tissue to kill microbes

DISINFECTION

Reducing the number of viable microorganisms present in a sample

QUATERNARY AMMONIUM COMPOUNDS (QUATS)

A type of disinfectant that is a cationic detergent

QUATERNARY AMMONIUM COMPOUNDS

QUATS means?

BACTERICIDAL

An antimicrobial that kills a microorganism

BACTERIOSTATIC

A condition where the multiplication of the bacteria is inhibited without killing them.

CHEMICAL DISINFECTION

Use of chemicals to kill or inhibit the growth of microorganisms

PHYSICAL DISINFECTION

Use of methods such as heat, UV light, and filtration to kill or inhibit organisms

GAS STERILIZATION

Uses ethylene oxide gas; used to sterilize objects that can’t be autoclaved like plastic products. A relative humidity of 30% can destroy bacterial spores

• ethylene oxide gas ; 30%

GAS STERILIZATION

• uses _____; used to sterilize objects that can’t be autoclaved like plastic products.

• A relative humidity of ____ can destroy bacterial spores

BLOOD-BORNE PATHOGENS

Are microorganisms in the blood or other body fluids that can cause illness and disease in people. They are transmitted through the blood.

MATERIAL SAFETY DATA SHEETS (MSDS)

A form with data regarding the properties of a particular substance. It may include instructions for the safe use and potential hazards associated with a particular material or product

MATERIAL SAFETY DATA SHEETS

MSDS means?

PERSONAL PROTECTIVE EQUIPMENT (PPE)

Includes all types of equipment used to increase individual safety while performing potentially hazardous tasks.

STANDARD PRECAUTIONS

Treat all blood and body fluids as potentially infectious and capable of transmitting HIV or other blood-borne diseases.

OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION (OSHA)

A US federal agency charged with the enforcement of safety and health legislation

OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION

OSHA means?

BIOLOGICAL SAFETY CABINETS (BSC)

These are hoods that are located in the laboratory. This is a type of containment barrier that protects the medical laboratory scientists from aerosol transmissions of microorganisms; handling of microbiological specimens should be performed in a BSC

BIOLOGICAL SAFETY CABINETS

BSC means?

1. Types of organisms

2. Number of organisms/microbial load/bioburden

3. Concentration of Disinfecting Agent

4. Presence of Organic Material

5. Nature of Surface to be Disinfected

6. Contact Time

7. Temperature

8. Biofilms

9. Compatibility of Disinfectants

FACTORS THAT INFLUENCE THE DEGREE OF KILLING ORGANISMS:

1-2 mins

Contact time for iodine and alcohol:

TEMPERATURE

directly proportional to the degree of disinfection

BIOFILMS

A community of bacteria that forms a protective material over them that protects them from environmental factors

1. Heat

2. Radiation

3. Filtration

4. Sonic and Ultrasonic Vibrations

PHYSICAL METHODS OF DISINFECTION:

HEAT

The most reliable method of sterilization of articles that can withstand heat.

HEAT

Acts by oxidative effects as well as denaturation and coagulation of proteins.

1. Nature of Heat

2. Temperature and Time

3. Number of Microorganisms Present

4. Species and Strain of Microorganism (Nature of Microorganism)

5. Type of Material

Factors that affect sterilization by heat:

Moist Heat

Which is more effective, dry heat or moist heat?

inversely

Temperature and time are (directly/inversely) proportional.

Hot air oven

Articles to be sterilized are exposed to high temperature in an electrically heated oven

protein denaturation

Dry heat acts by _____, oxidative damage and toxic effects of elevated levels of electrolytes.

• 60 minutes at 160°C

• 40 minutes at 170°C

• 20 minutes at 180°C

Different temperature-time relations for holding time are:

coagulation ; denaturation of proteins

Moist heat acts by _____ and _____.

121°C with 1/15 psi ; 132°C

The temp. of the autoclave is set at _____ for medical apparatus and ___ for medical waste.

RADIATION

Otherwise known as “cold sterilization.”

Cold sterilization

Radiation is otherwise known as?

100C ; 90 mins

Instead of keeping the articles in boiling water, they are subjected to free steam at ____for ___

1. Non-ionizing Radiation

2. Ionizing Radiation

2 TYPES OF RADIATION:

NON-IONIZING RADIATION

Are low energy rays with poor penetrative power

Inhibits DNA Replication

Mode of Action for non-ionizing radiation

IONIZING RADIATION

Are high-energy rays with good penetrative power

damages the nucleic acids of microorganisms

Mode of Action for ionizing radiation

FILTRATION

Does not kill microbes, it separates them out.

0.2-0.45 µm

Membrane filters with pore sizes between ____ are commonly used to remove particles from solutions that can't be autoclaved.

99.97% ; >0.3 um

HEPA filters are at least ___ efficient for removing particles___ in diameter

Membrane filters

Has pore sizes between 0.2-0.45 µm are commonly used to remove particles from solutions that can't be autoclaved.

HEPA filters

Are at least 99.97% efficient for removing particles >0.3 um in diameter

>20,000 cycle/second

Sound waves of frequency ____ kills bacteria by exposing them for one hour.

SONIC AND ULTRASONIC VIBRATIONS

This method is not reliable since many viruses are not affected by these waves.

1. Alcohols

2. Aldehydes

3. Halogens

4. Heavy Metals

5. Quaternary Ammonium Compounds

CHEMICAL METHODS OF DISINFECTION:

ALCOHOLS

Can’t kill spores and viruses.

ALCOHOLS

Disinfects by denaturing proteins.

ALDEHYDES

Inactivates DNA and RNA through alkylation of sulfhydryl groups.

PHENOL

Act by disruption of membranes, precipitation of proteins and inactivation of enzymes.

HALOGENS

They are oxidizing agents and cause damage by oxidation of essential sulfhydryl groups of enzymes.

HALOGENS

Commonly employed as surface disinfectants

HEAVY METALS

Precipitation of proteins and oxidation of sulfhydryl groups. They are bacteriostatic.

HYDROGEN PEROXIDE

It acts on the microorganisms through its release of oxygen.

HYDROGEN PEROXIDE

Produces hydroxyl-free radical that damages proteins and DNA

ETHYLENE OXIDE

It is an alkylating agent. It acts by alkylating sulfhydryl-, amino-, carboxyl- and hydroxyl- groups

1. Protein denaturation

2. Membrane disruption

3. Nucleic acid damage

4. Inhibition of metabolism

MECHANISMS OF ACTION OF CHEMICAL AGENTS:

RISK GROUP I

No or low individual risk.

RISK GROUP I

E. coli

RISK GROUP I

B. subtillis

RISK GROUP II

Moderate individual risk, low community risk.

RISK GROUP II

• Can cause mild disease, difficult to contract by aerosol.

• Treatment and preventive measures available

RISK GROUP II

Hepadna virus

RISK GROUP II

Influenza A

RISK GROUP II

Dengue fever

RISK GROUP II

HIV

RISK GROUP III

High individual risk, low community risk

RISK GROUP III

• Can cause serious disease.

• Can spread from one person to another.

• Treatment and preventive measures available

RISK GROUP III

Anthrax

RISK GROUP III

SARS

RISK GROUP III

TB

RISK GROUP III

Yellow fever

RISK GROUP IV

High individual risk and community risk

RISK GROUP IV

• Can cause serious disease.

• Readily transmitted from one individual to another.

RISK GROUP IV

Effective treatment and preventive measures are not usually available.

RISK GROUP IV

Marburg virus

RISK GROUP IV

Ebola

RISK GROUP IV

Hanta

RISK GROUP IV

Lassa

BIOSAFETY SAFETY CABINET (BSC)

These are hoods that are a type of containment barrier that protects the medical laboratory scientists from aerosol transmission of microorganisms.

UV light

Used to decontaminate the BSC after processing the specimen inside the BSC.

BSC Class I

It allows room air to pass into the cabinet, it only sterilizes the air going inside the cabinet.

BSC Class II

(most common in microbiology lab) – it sterilizes air that recirculates (inside) and exhausted (outside) by the cabinet.

BSC Class III

it completely protects the worker and is enclosed with negative pressure.

BSL-3

Most molecular labs are categorized as ___ because it involves negative airflow.

BSL 1

Not known to consistently cause diseases in immunocompetent adult humans.

BSL 1

Standard microbiological practices

BSL 1

Open bench top, sink required

BSL 2

Associated with human disease. Hazard: percutaneous injury, mucous membrane exposure, ingestion

BSL 2

• Limited access

• Biohazard warning signs

• Sharps precautions

• Biosafety manual defining waste decontamination or medical surveillance

BSL 2

• Non-fabric chairs and other furniture that’s easy to clean.

• Autoclave

• Eyewash readily available

BSL 3

Indigenous or toxic agents with potential for aerosol transmission; disease may have serious or lethal consequences.