Glossary of Terminology

Agar - A derivative of marine sea-weed, used as a solidifying agent in media.

Acid - A substance with a pH less than 7.

Aerobic - Grows in oxygen atmosphere.

Alkali - Substance with a pH greater than 7.

Algicide - A chemical agent which, under defined conditions, is capable of killing algae including their spores.

Amphoteric - A class of surfactant, having both anionic and cationic properties.

Anaerobic - Grows in oxygen free atmosphere.

Anionic - A surfactant in which the surface-active agent has a negative charge.

Antimicrobial - A substance capable of killing micro-organisms.

Antisepsis - The destruction or inhibition of micro-organisms on living tissues having the effect of limiting or preventing the harmful results of infection. It is not a synonym for disinfection.

Antiseptic - A chemical agent used in antisepsis.

Bacillus - A rod shaped bacteria.

Bactericide - A chemical agent which, under defined conditions, is capable of killing bacteria but not necessarily bacterial spores.

Bacteriostasis - A state of bacterial population in which, multiplication is inhibited.

Bacteriostat - A chemical agent which under defined conditions induces bacteriostasis

Biocide - A generalised term for a chemical agent capable of killing or inactivating micro-organisms. It embraces the more specific terms algicide, bactericide, fungicide, sporicide and viricide (see also germicide). Note. Pesticides are not considered to be biocides.

Cationic - A surfactant in which the surface-active agent has a positive charge.

Chemical Sterilizing Agent - A chemical agent which, under defined conditions, leads to sterilization.

Chlorhexidine - A bisphenol compound used as an antiseptic and disinfectant.

Chlorine - A member of the Halogen group of elements. Frequently, but usually, incorrectly used to define the active species in, e.g. solutions of sodium hypochlorite.

Coccus - A spherical bacterium.

Disease - Any change from a general state of good health.

Disinfectant - A chemical agent which under defined conditions is capable of disinfection.

Disinfection - The destruction of micro-organisms, but not usually bacterial spores: it does not necessarily kill all micro-organisms, but reduces them to a level acceptable for a defined purpose, for example, a level which is harmful neither to health nor to the quality of perishable goods.

DNA - Deoxyribonucleic acid. Protein that contains instructions for building other proteins.

Fumigation - Exposure of enclosed spaces to action of gaseous or vapour-phase disinfectants or sterilants.

Fungus - A group of diverse unicellular and multicellular microorganisms (pl. fungi)

Fungicide - A chemical agent which under defined conditions is capable of killing fungi including their spores.

Fungistasis - A state of fungal population the development of which is inhibited.

Fungistat - A chemical agent which under defined conditions induces Fungistasis.

Genus – A group of closely related species

Germ - A vague term which should be avoided. A micro-organism which can be harmful.

Germicide -A vague term which should be avoided. An agent under defined conditions, which is capable of killing germs.

Glutaraldehyde - A broad spectrum biocide used as an active ingredient in formulated disinfectants.

Gram-Negative - Gram-Negative bacteria do not have thick cell walls, and have a lipid membrane, making them harder to lyse.  Will give a negative result in a gram stain test.

Gram-Positive – Gram-Positive bacteria have thick, polar cell walls that are easier to lyse. Will give a positive result in a gram stain test.

Gram Stain - Stain technique used to classify bacteria into two groups: Gram negative or Gram positive.

Halogens - A group of chemicals consisting of e.g. Fluorine, Chlorine, Iodine and Bromine.

Hydrogen Peroxide - A bleaching/oxidising agent used as a disinfectant.

Hypochlorite - Usually sodium hypochlorite, solutions of hypochlorite are oxidising disinfectants producing the biocidally active hypochlorite anion and hypochlorous acid.

Iodine - A Halogen similar to chlorine but more stable and less reactive.

Iodophor – Iodine in solution of surfactant with stabiliser.

Lysis – The process of breaking open a cell’s membrane.

Lyse – To break open a cell’s membrane

Media - A nutrient rich solid or liquid (agar or broth) used to grow micro-organisms.

Microbe - An alternative expression for micro-organism.

Micro-organism - A microscopic entity capable of replication. It includes bacteria, viruses and the microscopic forms of algae, fungi and protozoa.

Motile - Describes organisms which can move independently.

Mould - Any fungus that forms visible mycelia growth.

Mycelium - A visible mass of tangled filaments of fungal growth.

Nucleic Acids - An organic compound composed of nucleotides DNA and RNA.

Oocyst - An oval body in the reproduction cycle of certain protozoa.

Pathogen - An organism that causes disease. Can be animals, plants or micro-organisms.

Peracetic acid - Organic peroxide of acetic acid, equilibrium mixture of acetic acid, hydrogen peroxide, and peracetic acid.

Phenol - Chemical derived from coal tar. Used as a disinfectant.

Preservation - Maintaining numbers of micro-organisms at low levels i.e. low enough to make food safe to eat or to prevent spoilage.

Protozoa - Unicellular micro-organisms. Classified in the Animal Kingdom.

Quaternary Ammonium Compound - A cationic surfactant with strong bactericidal but weak detergent properties.

RNA - Ribonucleic acid. Involved in protein synthesis.

Sanitisation - A term used mainly in the food and catering industry. A process of both cleaning/disinfecting utensils, equipment and surfaces.

Sanitiser - A chemical agent used for sanitization.

Somatic - Refers to the “body” or main part of a cell. Does not include reproductive structures such as spores.

Species - Fundamental rank of the classification system. (Two or more species grouped together are classed as a genus).

Spirochete - A twisted bacterial rod with a flexible cell wall containing axial filaments for motility.

Spore - A highly resistant structure formed from somatic cells in several genera of bacteria. E.g. Bacillus.  Also, a reproductive structure formed by fungi.

Sporicide - A chemical agent which, under defined conditions, is capable of killing bacterial spores.

Sterile - Free from all living micro-organisms.

Sterilisation - A process which renders an item sterile.

Sterilising agent - An agent or combination of agents which under defined conditions leads to sterilization.

Surfactant - A surface active agent.

Toxin - A poisonous substance produced by a species of micro-organism.

Vibrio - A form of bacteria occurring as a curved rod.

Viricide - A chemical agent which, under defined conditions, is capable of killing or inactivating viruses.

Virus - A non-cellular entity consisting of protein and nucleic acid. Can only replicate after entry into specific types of living cell.

Zoonosis - Any disease which can be transmitted from animal to man and vice-versa.