Microbiology Control Methods Flashcards

A set of vocabulary flashcards covering the physical and chemical methods of microbial control, including terminology, heat treatments, radiation, and chemical agents.

Sterilization

The complete removal or destruction of all viable microorganisms, including viruses and bacterial endospores, usually on inanimate objects.

Disinfection

The destruction or removal of vegetative pathogens, but not bacterial endospores, from inanimate surfaces.

Antisepsis (Degermation)

The application of chemical agents to living body surfaces, wounds, or surgical incisions to destroy or inhibit vegetative pathogens.

Decontamination (Sanitisation)

The mechanical removal of most microbes from animate or inanimate surfaces to reduce contamination to safe levels.

Bacterial endospores

Considered the most resistant microbial entities; their destruction is the primary goal of sterilization.

Sepsis

The growth of microorganisms in the blood and other body tissues.

Asepsis

Any practice that prevents the entry of infectious agents into sterile tissues and thus prevents infection.

Bactericide

A chemical agent that destroys bacteria except for those in the endospore stage.

Sporicide

A chemical agent capable of killing bacterial endospores.

Microbistatic agents

Chemicals, such as antiseptics and drugs, that prevent microbes from multiplying without necessarily killing them.

Critical medical devices

Medical items expected to come into contact with sterile tissues.

Semicritical medical devices

Medical items that come into contact with mucosal membranes.

Noncritical medical devices

Items that do not touch the patient or are only expected to touch intact skin.

Microbial death

The permanent loss of reproductive capability, even under optimum growth conditions.

Native state

The normal three-dimensional configuration of a protein that allows it to function properly.

Denature

The disruption of a protein's secondary and tertiary structure, rendering it nonfunctional.

Autoclave

A device that uses steam under pressure to achieve sterilization, typically at $15\,psi$ and $121\,^{\circ}C$ for $20\,min$.

Pasteurization

A technique using heat on liquids to kill agents of infection and spoilage while retaining flavor and food value.

Incineration

A dry heat method that ignites and reduces microbes to ashes and gas, reaching temperatures up to $6,500\,^{\circ}C$.

Lyophilization

A process of freeze-drying where water is removed by a high-powered vacuum at low temperatures to preserve specimens.

Ionizing radiation

A high-energy, short wavelength sterilization method (Gamma rays and X-rays) that causes catastrophic mutations in DNA.

Nonionizing radiation

Ultraviolet (UV) radiation that causes the formation of pyrimidine dimers in DNA; most lethal at $240\,nm$ to $280\,nm$.

Tinctures

Antimicrobial chemicals dissolved in pure alcohol or water–alcohol mixtures.

Aqueous solutions

Solutions containing pure water as the solvent.

Quaternary ammonium compounds (quats)

A type of surfactant used as a low-level disinfectant for sanitizing objects and surfaces.

Oligodynamic

The property of being toxic in minute quantities, used to describe heavy metal compounds like mercury and silver.

Glutaraldehyde

A rapid, broad-spectrum liquid sterilant that kills endospores in $3\,hr$ and works in the presence of organic matter.

Ethylene oxide

A gaseous sterilant used in a chemiclave for delicate hospital instruments and heat-sensitive plastics.

Sterilization

The complete removal or destruction of all viable microorganisms, including viruses and bacterial endospores, usually on inanimate objects.

Disinfection

The destruction or removal of vegetative pathogens, but not bacterial endospores, from inanimate surfaces.

Antisepsis (Degermation)

The application of chemical agents to living body surfaces, wounds, or surgical incisions to destroy or inhibit vegetative pathogens.

Decontamination (Sanitisation)

The mechanical removal of most microbes from animate or inanimate surfaces to reduce contamination to safe levels.

-cidal agents

Agents that kill microorganisms.

-static agents

Agents that inhibit the growth and reproduction of microorganisms without necessarily killing them.

Factors affecting death rate

Factors include the initial population size, the population composition, the concentration of the agent, and the duration of exposure.

Physical Control Methods

Includes methods like heat, cold, radiation, filtration, and osmotic pressure to control microbial growth.

Moist heat methods

Include autoclaving, boiling, and pasteurization.

Dry heat methods

Include oven sterilization, incineration, and dry heat sterilization.

Autoclaving

Uses steam under pressure to achieve sterilization, typically at $15\,psi$ and $121\,^{\circ}C$ for $20\,min$.

Hot air sterilization

Uses dry heat to sterilize but requires longer time and higher temperatures compared to autoclaving.

Cold methods

Includes refrigeration, freezing, and lyophilization (freeze-drying).

Ionizing radiation

High-energy, short wavelength radiation (gamma & X-ray) that causes catastrophic mutations in DNA.

Nonionizing radiation

Ultraviolet (UV) radiation that causes the formation of pyrimidine dimers in DNA; most lethal at $240\,nm$ to $280\,nm$.

Filtration

Removes microbes from liquids and air and can be used on heat-sensitive solutions.

Osmotic pressure

High concentrations of salt or sugar that prevent microbial growth by inducing plasmolysis.

Halogens

Chemical agents such as chlorine and iodine used for sterilization and disinfection.

Phenol & derivatives

Include compounds like cresols and bisphenols, recognized for their disinfecting properties.

Alcohols

Ethanol and isopropyl alcohol, commonly used at $70\%$ concentration for disinfection.

Oxidizing agents

Chemical agents like hydrogen peroxide that can sterilize and disinfect using oxidative reaction.

Detergents

Comprise quaternary ammonium compounds and soaps used for cleaning and disinfection.

Heavy Metal compounds

Compounds like mercury and silver nitrate, known for their antimicrobial properties but with notable drawbacks.

Aldehydes

Include glutaraldehyde, formaldehyde, and ortho-phthalaldehyde, effective as disinfectants and sterilizers.

Gaseous sterilants

Ethylene oxide, a gas used for sterilizing heat-sensitive instruments and materials.

Sterilizer vs Disinfectant

Sterilizers eliminate all forms of microbial life, while disinfectants reduce pathogenic organisms but may not eliminate all pathogens.