Lecture 2: Disinfection and Sterilization Flashcards
Define antiseptic
substance that prevents or arrest growth of microorganisms, substance applied to living tissues
define asepsis
prevention of contact with microorganisms
define autoclave
device that sterilizes instruments or other objects using steam under pressure
define disinfectant
chemical or physical agent that destroys microorganism, substance applied to inanimate objects
define nosocomial infection
infection acquired in hospital by patient who was administer for a reason other than that infection. Infection was not present or incubating at time of admission
define sanitizer
agent that reduces the number of bacterial contaminants to safe levels as judged by public health requirements
define sterile
state of being free from all living microorganisms
define sterilization
process used to render a produce free of all forms of viable microorganisms
what is a low level disinfectant used for
vegetative bacteria, fungi, influenza viruses
what is an intermediate disinfectant used for
enteroviruses, mycobacterium tuberculosis
what is a high level disinfectant used for
bacterial and fungal spores
what are the types of physical and chemical sterilization
- Physical: heat, filtration, radiation
- Chemical: ethylene oxide, hydrogen peroxide
what is the MOA of steam sterilization
destroys microorganisms by the irreversible coagulation and denaturation of enzymes and proteins
what are the 4 parameters needed for steam sterilization of instruments and packs
- Steam
- Pressure
- Temperature
- Time
what is the ideal steam for sterilization
dry saturated steam
how does high pressure help with steam sterilization
helps attain higher temperatures
what are ideal temperatures for steam sterilization
121 C (250 F) and 132 C (270 F)
what are the time periods needed for steam sterilization at both temperatures
- 30 minutes at 121 C (250 F) in gravity displacement sterilizer
- 4 minutes at 132 C (270 F) in pre vacuum sterilizer
mechanical indicators of sterilization won’t detect __
loading problems
what are the chemical sterilization monitors/indicators
temperature sensitive tape, steam markers
what is an example of a biological sterilization monitor/indicator
geobacillus stearothermophilus spores (heat resistant), dead spores= all microorganisms exposed will be dead
what is flash sterilization
sterilization of an unwrapped object at 132 C (270F) for 3 minutes at 27-28lbs of pressure in a gravity displacement sterilizer
when do you use flash sterilization
emergences- insufficient time to sterilize by other methods
what is the most commonly used process for sterilizing temperature and moisture sensitive devices
ethylene oxide
what is the MOA of ethylene oxide chemical sterilization
alkylation of a protein, DNA, and RNA which prevents normal cel metabolism and replication. Kills bacteria, spores, fungi and live viruses
what are the disadvantages of ethylene oxide chemical sterilization
- Lengthy cycle time -12hrs
- Flammable and explosive
- Toxicity
what are the 5 stages of ethylene oxide cycle
- Purging/humidificaiton
- Gas introduction
- Exposure at least 12hrs
- Evacuation
- Air washes- 12-24hrs
what is the MOA of vaporized hydrogen peroxide chemical sterilization
generation of destructive free radicals that react with and kill microorganisms
what are the advantages of vaporized hydrogen peroxide vs ethylene oxide
- Less toxic
- Shorter cycles
what is MOA of ionizing radiation sterilization
damages DNA or microorganisms
what is ionizing radiation used for
all prepackaged equipment
what is cold sterilization used for
- Soaking instruments in disinfectant solution- commonly dental supplies and minor surgery equipment
- Surgical equipment- lenses instruments, metals, rubber, plastic
