Learn: Microbiology Module 4

Sterilization

The process that completely destroys all microbes, including endospores and viruses.

Sterilization's common use

surgical instruments and syringes

Autoclave

A sterilization technique that uses high temperature, high pressure and moisture.

Disinfection

The process of destroying vegetative pathogens and most microbes, using physical or chemical means. Only for inanimate objects.

Disinfecting agents/techniques

Bleach, iodine and boiling

Disinfection's common use

examination tables, food prep areas and thermometers

Decontamination/Sanitization

a cleansing technique that mechanically removes microorganisms as well as other debris to reduce contamination to safe levels

Decontamination's/Sanitization's common use

cooking utensils, dishes, bottles and cans

Decontamination/Sanitization agents/techniques

soap, detergents and commercial dish washers

Antisepsis/degermation

decontamination of living surfaces, using sterile methods

Sepsis

Growth of microbes in blood and other tissues

Asepsis

The practice of preventing entry of infectious agents into tissues

Bactericide

kills vegetative bacteria

Fungicide

kills fungus spores

Virucide

kills viruses

Sporicide

specifically kills bac. endospores, can also kill veg. bacteria

Germicide/microbiocide

kills microbes

Endospores are resistant to...

heat, drying, freezing, radiation and chemicals

Sporulation

"spore formation" induced by environmental conditions, ex. vegetative cell on an examination table

Sporangium

vegetative cell that has turned into a sporulating cell, this transformation takes 6-8 hours

Germination

During favorable conditions (bad environment) where the spore releases a vegetative cell, water & nutrients are needed

Pasteurization

Disinfection of beverages contaminated without losing flavor or food value and decreasing microbial load, NOT sterilization

Thermal death time

Minimum TIME required to kill all microbes at a specified temperature, high temp low time

Thermal death point

Minimum TEMPERATURE required to kill all microbes in 10 minutes

Radiation

Energy emitted from atomic actives and dispersed at high velocity through matter or space

Irradiation

Bombardment of microbes with radiation

Ionizing radiation

Gamma rays and x-rays, DNA breaks, protein damage (ex. cold sterilization)

Non-ionizing radiation

UV radiation, crosslinks DNA, no replication or protein production, easily blocked (ex. air handling system)

Aqueous solution

A chemical dissolved in water

Tincture

A chemical dissolved in alcohol or water alcohol mixtures, preps skin for surgery

Sterilizing agents

Halogens, Hydrogen peroxide, Aldehydes and Ethylene oxide

Halogens

Sterilizing agents, chlorine and iodine

Chlorines

liquid, gas (ex. bleach). can denature enzymes. less effective with: light exposure, high pH or excess organic matter (blood, saliva etc.)

Iodines

liquid, penetrates cells and interferes with metabolic functions, can be irritating/toxic

Iodophers

complex of iodine bound to alcohol, does not sterilize instead DISINFECTS

Hydrogen peroxide

liquid, produces toxic reactive oxygen, works best at high concentrations and an expired agent will likely fail due to instability over time

Hydrogen peroxide use

Aseptic: skin and wound care

Disinfectant: contact lenses, implants and plastic equipment

Sterilization: delicate reusable instruments

Aldehydes

organics with a -CHO functional group, disrupts enzymes and DNA, extremely toxic

Glutaraldehyde

Rapid action

Formaldehyde/Formalin

Slower action

Chemiclave

chemical sterilization

Ethylene oxide

colorless gas, reacts with functional groups of proteins and DNA, plastic and delicate instruments, explosive and tissue damage, sterilizes at lower temperatures

Disinfecting agents

Phenol and surfactants

Surfactants examples

Detergents, alcohol, soap and quats

Phenol

liquid, very toxic, disrupts cell wall, membranes and enzymes (ex. triclosan- antibiotic), disinfectant and antiseptic chemicals added to many products: soaps, plastics, toothpaste/cosmetics, TOYS, can lead to antibiotic resistance

Surfactants definition

inhibited by organic matter, ineffective against spores and many veg. bacteria, binds to lipid layer and penetrates hydrophobic region, creates leaks and lysis

Alcohols

liquid, cannot kill endospores, for microbe control only ethyl and isopropyl alcohol are appropriate, must be high concentration, evaporation limits effectiveness, low exposure time

Soap

weakens microbes, Pseudomonas grow abnormally in soap dishes, used mechanically

Quaternary Ammonium Compounds (Quats)

positive charge with central nitrogen atom, breaks down cell membrane, used for objects and surfaces

Filtration

removes microbes from air and liquids, filter allows liquid or air to pass; NOT microbes, used for liquids that cannot withstand heat (ex. eyedrops)