BIOL 250 - Chapter 9 Vocab

Sterilization

removal or destruction of all microbes; less strictly, only the eradication of harmful microorganisms and viruses(some innocuous microbes may still be viable)

Commercial sterilization

does not kill all hypothermophilic microbes because they do not cause disease and cannot grow to spoil food

Aseptic

describes an environment or procedure that is free of contamination by pathogens(ex

Disinfection

the use of physical or chemical agents(disinfectants) to inhibit or destroy microorganisms; does NOT guarantee that all pathogens are eliminated; used only in reference to inanimate objects

Antisepsis

when a chemical is used on skin or tissue, the chemical used is called an antiseptic

Degerming

removal of microbes from a surface by scrubbing(ex

Sanitization

process of disinfecting places and utensils used by the public to reduce the number of pathogenic microbes to meet accepted public health standards(ex

Pasteurization

the use of heat to kill pathogens and reduce the number of spoilage microorganisms in food and beverages

Microbial Death

the permanent loss of reproductive ability under ideal environmental conditions

High-level germicides

kill all pathogens, including bacterial endospores; used by health care professionals to sterilize invasive instruments

Intermediate-level germicides

kill fungal spores, protozoan cysts, viruses, and pathogenic bacteria, but not endospores; used to disinfect instruments that come in contact with mucous membranes but are noninvasive, such as respiratory equipment and endoscopes

Low-level germicides

eliminate vegetative bacteria, fungi, protozoa, and some viruses; they are used to disinfect items that contact only the skin of patients, such as furniture and electrodes.

Biosafety level 1

suitable for handling microbes, such as E.coli, not known to cause disease in healthy humans; minimal precautions like hand-washing and disinfecting surfaces

Biosafety level 2

designed for handling moderately hazardous agents, like hepatitis and the flu; access to these labs is limited when work is being conducted

Biosafety level 3

requires all manipulations be done within safety cabinets containing high-efficacy particulate air filters, and specifies special design features for the lab; entry through double sets of doors and lower air pressure in the lab; air leaving the room is HEPA filtered; designed for experimentation on microbes

Biosafety level 4

designed for working with dangerous or exotic microbes that cause severe or fatal disease in humans, such as Ebola; either separate buildings or found in completely isolated areas of their building; entry and exit controlled by electronically sealed airlocks with multiple safety precautions designed to destroy all traces of the biohazard ; all air and water is filtered, and personnel must wear “space suits”

Thermal death point

the lowest temperature that kills all cells in a broth in 10 minutes

Thermal death time

the time it takes to sterilize a particular volume of liquid at a set temperature

Decimal reduction time

the time required to destroy 90% of the microbes in a sample(used to measure effectiveness of heat sterilization)

Boiling

kills the vegetative cells of bacteria and fungi, the trophozites of protozoa, and most viruses within 10 minutes at sea level(effective for sanitizing restaurant tableware and disinfecting baby bottles)

Autoclaving

used to sterilize chemicals and objects that can tolerate moist heat; pressure is applied to boiling water to prevent the escape of heat in steam

Pasteurization

heating liquids at high temperatures for shorts amount of times

Ultra-high-temp sterilization

involves flash heating milk or other liquids to rid them of all living microbes; involves passing liquid through superheated steam and then cooling it rapidly; treated liquids can be stored indefinitely at room temp without microbial spoilage(ex. Creamer packets)

Desiccation

drying; inhibits microbial growth because metabolism requires liquid water

Lyophilization

a technique that combines freezing and drying to preserve microbes and other cells for many years; scientists instantly freeze a culture in liquid nitrogen or frozen carbon dioxide, then they subject it to a dry vacuum that removes frozen water through sublimation, where its transformed from solid to gas directly

Filtration

the passage of a fluid(liquid or gas) through a sieve designed to trap particles(cells and viruses) and separate them from the fluid; traps microbes larger than pore size, allowing smaller microbes to pass through

Osmotic pressure

use of high concentrations of salt and sugar in foods to inhibit microbial growth

Ionized radiation

electron beams, gamma rays, and some Xrays, all of which have wavelengths shorter than 1 nm; when they strike molecules, they have sufficient energy to eject electrons from atoms, creating ions; such ions denature other molecules, particularly DNA, causing fatal mutations and cell death

Non-ionizing radiation

electromagnetic radiation with a wavelength greater than 1 nm that does not have enough energy to force electrons out of orbit; however, it does have enough energy to excite electrons and cause them to make new covalent bonds, which can affect the 3D structure of proteins and nucleic acids (ex

Chemical methods of microbial control

adversely affect microbes’ cell walls, cytoplasmic membranes, proteins, or DNA; tend to destroy or inhibit the growth of enveloped viruses and the vegetative cells of bacteria, fungi, and protozoa more than fungal spores, protozoan cysts, or bacterial endospores

Phenols and phenolics

phenol and compounds derived from phenol molecules that have been additionally been chemically modified; they denature proteins and disrupt cell membranes in a wide variety of pathogens; they are effective even in the presence of contaminating organic material, and they remain active on surfaces for a prolonged time; commonly used in healthcare settings, labs, and households; disagreeable odor

Alcohols

bactericidal, fungicidal, and virucidal against enveloped viruses, but not effective against fungal or bacterial endospores; considered intermediate level disinfectants; denature proteins and disrupt cytoplasmic membranes; evaporate rapidly

Halogens

iodine, chlorine, bromine, fluorine; intermediate level antimicrobial chemicals that are effective against vegetative bacterial and fungal cells, fungal spores, some bacterial endospores and protozoan cysts, and many viruses; exert their antimicrobial effect by unfolding and denaturing essential proteins including enzymes

Oxidizing agents

high level disinfectants and antiseptics that work by releasing oxygen radicals, which are particularly effective against anaerobic microorganisms; used by health care workers to kill anaerobes in deep puncture wounds

Hydrogen peroxide

common household chemical that can disinfect and even sterilize surfaces of inanimate objects such as contact lenses; should NOT be used to treat open wounds

Ozone

reactive form of oxygen that gives air its “fresh” smell after a thunderstorm

Peracetic acid

extremely effective sporicide that can be used to sterilize surfaces; used by food processors and medical personnel to sterilize equipment because it leaves no toxic residue

Surfactants

“surface active” chemicals; act to reduce the surface tension of solvents such as water by decreasing the attraction among molecules, making the solvent more effective at dissolving solute molecules (ex

Heavy metals

ions of relatively high density metals, that are toxic at low concentrations; antimicrobial because they combine with sulfur atoms, denaturing proteins; low level bacteriostatic and fungistatic agents

Aldehydes

compounds containing terminal -CHO groups; cross link organic functional groups, denaturing proteins and inactivating nucleic acids

Gaseous agents

rapidly penetrate paper and plastic wraps, diffusing into every crack and denaturing proteins and DNA by cross linking functional groups, killing everything they come into contact without harming inanimate objects; highly explosive, extremely poisonous, and potentially carcinogenic

Enzymes

enzymes that act against microorganisms

Antimicrobial drugs

chemotherapeutic agents that treat infections