Lecture 10 Chapter 11

What is sterilization?

The destruction or removal of all microbial life

What is disinfection?

The destruction of microorganisms on nonliving objects

What is sepsis?

The presence of harmful microorganisms or their products in tissues or body fluids

What is antisepsis?

Disinfection performed on living tissue

What is degerming?

The removal of microbes from a limited area

What is pasteurization?

A heat treatment used to reduce microbial populations in foods or beverages without sterilizing them

What is sanitization?

Reduction of microbial populations to safe public-health levels

What is preservation?

Using methods that inhibit microbial growth and prolong the usefulness of materials

What is a critical item?

An item that enters sterile tissue or the vascular system and requires sterilization

What is a semi-critical item?

An item that contacts mucous membranes and requires appropriate disinfection

What is a noncritical item?

An item that contacts intact skin and generally requires lower-level disinfection

Which is more resistant to microbial control: prions or fungal spores?

Prions

Which is more resistant: fungal spores or gram-positive bacteria?

Fungal spores

What is the difference between bactericidal and bacteriostatic?

Bactericidal agents kill bacteria while bacteriostatic agents inhibit bacterial growth

What factors affect disinfectant action?

Contact time, temperature, pH, bioburden, microbe type, extraneous matter, exposure, concentration, and infection risk

What are two major ways antimicrobial agents work?

They alter cell walls or membranes and interfere with proteins or nucleic acids

What cellular structures can physical and chemical control agents target?

Cell walls, cytoplasmic membranes, DNA, RNA, and proteins

What are the three major physical methods of microbial control discussed?

Heat, cold, and radiation

What is moist heat's major effect on microbes?

Coagulation of cellular proteins

What is dry heat's major effect on microbes?

Dehydration, coagulation, and oxidation

What is an autoclave?

A device that sterilizes using steam under pressure

What temperature and time are associated with autoclaving in the presentation?

121°C for 15 minutes

Is an autoclave a sterilization method?

Yes

What is thermal death time?

The shortest time required to kill all test microbes at a specified temperature

What is thermal death point?

The lowest temperature required to kill all microbes in a sample in 10 minutes

How does increasing temperature affect the required exposure time?

Higher temperatures allow shorter exposure times

How does decreasing temperature affect the required exposure time?

Lower temperatures require longer exposure times

What is Tyndallization?

Repeated treatment with free-flowing steam used for some heat-sensitive materials

Does pasteurization sterilize a product?

No

What is pasteurization used for?

Foods and beverages

What are three types of radiation useful for microbial control?

Gamma rays, X rays, and ultraviolet radiation

What is ionizing radiation?

Radiation such as gamma rays and X rays that can penetrate deeply and damage cellular components

What can ionizing radiation damage?

Proteins, DNA, and organelles

What is non-ionizing radiation used for microbial control?

Ultraviolet radiation

What is the main target of UV radiation?

DNA

Why is UV radiation less useful for deep sterilization?

It has low penetrating ability

What is filtration used for?

Removing microorganisms from liquids or air that cannot tolerate heat or chemicals

What is a depth filter?

A filter that retains bacteria through pores and charge

What is a limitation of depth filters?

They may not retain viruses

What is a membrane filter?

A filter with pores designed to retain microorganisms from liquids

What does HEPA stand for?

High Efficiency Particulate Air

What are antimicrobial chemicals?

Chemical agents used to control microorganisms

What factors must be considered when choosing a chemical antimicrobial?

Microbe type, concentration, organic matter, temperature, pH, surface, time, and concentration

What is a desirable quality of a germicide?

Rapid action at low concentrations

What does broad-spectrum mean for a germicide?

It is effective against many types of microorganisms

What are the three levels of chemical germicides?

High-level, intermediate-level, and low-level

What can high-level germicides kill?

Endospores when properly used

What can intermediate-level germicides kill?

Fungi and resistant pathogens such as the tubercle bacillus, as well as viruses

What can low-level germicides eliminate?

Vegetative bacteria, vegetative fungal cells, and some viruses

What are common alcohols used as antimicrobial agents?

Ethanol and isopropanol

How do alcohols control microbes?

They disrupt cell membranes and coagulate proteins

Are alcohols endosporocidal?

No

What concentration range of alcohol is associated with antimicrobial activity in the presentation?

50-95%

What are halogens?

Fluorine, bromine, chlorine, and iodine

How does chlorine help kill microorganisms?

It forms hypochlorous acid that oxidizes groups and interferes with proteins and enzymes

What can inactivate halogens?

Light, high pH, and organic matter

What is bleach?

Sodium hypochlorite

What is chlorine commonly used to treat?

Drinking water and wastewater

What are common uses of iodine?

Skin antisepsis and water disinfection

What are iodophors?

Complexes of iodine and alcohol

What is glutaraldehyde?

A broad-spectrum chemical accepted as a sterilant

What is an advantage of glutaraldehyde?

It retains potency in the presence of organic matter

What is a disadvantage of formaldehyde?

It is extremely toxic

What are phenolics?

Chemical germicides including phenol, cresols, bisphenols, and chlorinated phenols

What are quaternary ammonium compounds commonly called?

Quats

What is a major action of surfactants?

They disrupt the selective permeability of the cytoplasmic membrane

What is an oligodynamic agent?

A substance that is toxic to microbes in minute quantities

Which heavy metals have significance as germicides in the presentation?

Mercury and silver

What is silver sulfadiazine used for?

Burn treatment

What is ethylene oxide used for?

Chemical sterilization

Why must ethylene oxide be handled carefully?

It is explosive and carcinogenic

What is chlorine dioxide used for?

Treatment of water and wastewater and disinfection of equipment and medical waste

What are organic acids used for?

Food preservation

What are examples of organic acids used in food preservation?

Acetic, propionic, lactic, benzoic, and sorbic acids

How can cold storage inhibit microbial growth?

It slows microbial activity and growth

How can high salt or sugar inhibit microbes?

It creates osmotic stress

How does desiccation inhibit microbial growth?

It removes water needed for microbial activity

What is lyophilization?

Freeze-drying used to preserve materials

What chemical preservative inhibits Clostridium botulinum germination according to the presentation?

Nitrites