Sterilization and Disinfection Flashcards
What is Sterilization
Sterilization: the complete removal or destruction of all living organisms on an item or in a solution (item is then called sterile).
What is Disinfection
Disinfection: the reduction of the number of microorganisms so that it is unlikely to cause infection (spores are not affected).
What is Antiseptic
Antiseptics: are disinfectants that can be applied on living tissue (e.g. skin or wound).
What is Aseptic technique
Aseptic technique: a procedure in which added precautions are followed to prevent contamination by microorganisms. (e.g. venipucture).
STERILIZATION by heat
• Incineration: used for disposal of infectious waste materials (>800°C).
• Dry Heat: (Oven) usually used for glassware (160°C for 2hrs).
• Moist heat (Autoclave): Used for heat-resistant material and culture media (121°C for 15
min under 1 atmospheric pressure).
STERILIZATION by radiation
Exposure of an organism to ionizing radiation (irradiation) such as x-rays and gamma rays causes damage in DNA strand, leading to bacterial cell death.
• Used in industry to sterilize single-use items such as needles, syringes, gloves, etc.
STERILIZATION by Filtration
Air filtration • High Efficiency Particulate Air (HEPA) filters are used in biological safety cabinets, and in isolation and operating rooms. • It efficiently removes particles larger than 0.3μm in size from air. • Filters become gradually saturated (blocked) with use, so they need to be regularly replaced.
STERILIZATION by Membrane filtration
Used to remove bacteria and larger organisms from heat-sensitive liquids, such as antibiotic solutions or serum.
• Usually a pore size of 0.22 or 0.45μm is used (will not remove viruses).
STERILIZATION byChemical sterilization
Chemical sterilization
• Ethylene oxide (EtO) in gaseous form.
• Used in industry to sterilize heat-sensitive materials (plastics and electronic instruments).
• Other chemical sterilizers include: formaldehyde and glutaraldehyde.
What is Central Sterile Supply Department (CSSD):
A specialized unit in hospitals that carry out cleaning, disinfection, sterilization, and packaging of medical supplies and instruments.
Biological indicators for STERILIZATION .
. Consist of a vial that contains bacterial spores (Bacillus stearothermophilus) and a pH indicator.
. After sterilization, the tube is incubated, which should result in no growth of organism (i.e. no color change).
Chemical indicators for STERILIZATION
Autoclave tape is an adhesive tape that is attached to items before autoclaving, and contains a chemical that changes color when the correct temperature is reached (about 121°C). •Autoclave strip: a strip that indicates that both the correct temperature & pressure were reached.
DISINFECTION by heat
Heat Hot water (moist heat) -Hot water (60°C) for 1 hour or boiling (100°C) for 15 min. -Will kill vegetative organisms, but spores will not be destroyed.
Pasteurization -At 72°C for 15 seconds. -Will reduce microbial load and kill pathogenic bacteria. -Commonly used for milk and beverages. -A modification is Ultra-high temperature (UHT) at 134°C for 5 seconds for producing long-life beverages (sterile).
DISINFECTION by radiation
Ultraviolet (UV) rays: must have direct surface exposure. - Generated from a UV lamp (germicidal range 200-280nm) - Exposure leads to formation of abnormal bonds in the DNA strands (mutations). - Can be used to disinfect working surfaces ( e.g. inside safety cabinets).
DISINFECTION by chemical
There are three levels of chemical disinfectants: •High level: kills vegetative organisms and a large number of spores. •Intermediate-level: kills vegetative organisms and some spores. •Low-level: kills only vegetative organisms.
