Controlling Microbial Growth In The Environment Flashcards
(25 cards)
Antisepsis
Reduction in the number of microorganisms and viruses, particularly potential pathogens on living tissue
Aseptic
Refers to an environment or procedure free of pathogenic contaminants
-cide or -cidal
Suffixes indicating destruction of a type of microbe
Degerming
Removal of microbes by mechanical means
Disinfection
Destruction of most microorganisms and viruses on non-living tissue
Pasteurisation
Use of heat to destroy pathogens and reduce the number of spoilage microorganisms in food and beverages
Sanitisation
Removal of pathogens from objects to meet public health standards
- stasis
- static
Suffixes indicating inhibition but not complete destruction of a type of microbe
Sterilisation
Destruction of all microorganisms and viruses in or on an object
Action of antimicrobial agents
Alteration of cell walls - when damaged effects of osmosis can cause cell to burst
Cytoplasmic membrane- contents leak out
Non-enveloped viruses can better tolerate harsh conditions
Damage to proteins and nucleic acids -alter or destroy, fatal mutants, halt synthesis
Most resistant to least resistant
Prions Bacterial endospores Mycobacterium Cysts of Protozoa Active stage Protozoa (trophozoites) Most gram negative bacteria Fungi Nonenveloped viruses Most gram positive bacteria Enveloped viruses
High level germicides
Kill all pathogens including endospores
Intermediate-level germicides
Kill fungal spores, protozoan cysts, viruses and pathogenic bacteria
Low-level germicides
Kill vegetative bacteria, fungi, Protozoa and some viruses
Moist heat
Used to disinfect, sanitise, sterilise and pasteurise
Denatures proteins and destroys cytoplasmic membranes
More effective than dry heat
Boiling
Autoclaving
Pasteurisation
Ultrahigh-temperature sterilisation
Desiccation and lyophilisation
Desiccation (drying) inhibits growth due to removal of water
Lyophilisation (freeze-drying) used for long term preservation of microbial cultures - prevents formation of damaging ice crystals
Radiation
Particulate radiation - high speed sub atomic particles
Electromagnetic radiation - energy without mass travelling at the speed of light
Phenol and phenolic
Denature proteins and disrupt cell membranes
Effective in presence of organic matter
Remain active for prolonged time
Commonly used in health care settings, labs and homes
Have disagreeable odour and possible side effects
Alcohols
Intermediate-level disinfectants
Denature proteins and disrupt cytoplasmic membranes
More effective than soap
Swabbing skin with alcohol prior to injection removes most microbes
Halogens
Include iodine, chlorine, bromine and fluorine
Intermediate-level antimicrobial chemicals
Damage proteins by denaturation
Oxidising agents
Peroxide’s, ozone, and peracetic acid Kill by oxidation of microbial enzymes High-level disinfectant Hydrogen peroxide can disinfect and sterilise wounds because of catalase activity Ozone treatment of drinking water
Surfactants
Surface active chemicals
Reduce surface tension of solvents
Soaps and detergent
Low-level disinfectants
Heavy metals
Heavy-metal ions denature proteins
Low-level bacteriostatic and fungistatic agents
Thimerosal used to preserve vaccines
Copper controls algal growth
Aldehydes
Compounds containing -CHO groups
Denature proteins and inactivate nucleic acids
Glutaraldheyde disnifects and sterilises
Formalin used in embalming and in disinfection of rooms and instruments
