CH.8 - Control of Microorganisms in the Environment

biocide

all antimicrobial agents that can be used to control microbes

sterilization

process by which all living cells are either destroyed or removed from an object/habitat

disinfection

the killing, inhibition, or removal of microorganisms that may cause disease (usually on objects)

sanitation

reduction in the microbial population on an object to levels judge safe by public health standards

sterilant

a chemical whose use results in the destruction of all life and infectious agents on an object

antisepsis

prevention of infection in living tissue

antiseptic

a chemical agent used to control microbial growth on living tissue

bactericide

agent that kills bacteria

fungicide

agent that kills fungi

viricide

agent that inactivates viruses so that they cannot reproduce wn/ a host cell

bacteriostatic

inhibit the growth and reproduction of bacteria

decimal reduction time (D value)

time required to kill 90% of microorganisms or endospores in a sample at a specified time; measure in time

depth filters

a filter composed of fibrous/granular materials in a thick layer w/ narrow channels that are used to decrease the microbial load and sterilize solutions

autoclave

- an apparatus for sterilizing objects by the use of steam under pressure (121°C and 15lbs)

- color change in tape indicates that it has been heated

- verification = measured by including bacterial endospores in the run and testing their viability following the run

pasteurization

process of heating a temperature-sensitive liquid to temperatures below boiling for the purpose of killing undesirable microbes

ionizing radiation

gamma radiation that penetrates deep into objects destroying bacterial endospores and all microbial cells except viruses

UV radiation

causes thymine dimers to prevent replication and transcription; surface sterilization (260nm is most effective)

phenolics

disinfectant that denatures proteins and disrupts cell membranes

alcohols

dissolve membrane lipids and denature proteins

halogens

iodine (skin antiseptic) and chlorine (municipal water supply)

Heavy metals

once used as germicides (via complex w/ sulfhydryl) to inactivate proteins

quaternary ammonium compounds

antimicrobial detergents that have the ability to denature proteins and disrupt microbial membranes

ethylene oxide

kills microbes and spores and is primarily used to sterilize heat-sensitive materials (alkylates nucleic acids and proteins)

sterilizing gases

sporicidal and microbicidal (i.e. ethylene oxide and chlorine dioxide)

copper

an effective algicide

antimicrobial effectiveness

measured by concentration of agent, duration of exposure, and temperature