Bacterial Decontamination, Sterilization & Disinfection Flashcards
What is the difference between decontamination, disinfection, and sterilization?
DECONTAMINATION: cleaning and any additional steps required to eliminate risk of infection while handling devices or attire - a reduction in potentially pathogenic organisms to a level that is safe to handle
DISINFECTION: elimination of most, if not all, pathogenic organisms, including spores, usually by chemical means - most effective when preceded by cleaning
STERILIZATION: elimination of all living organisms
Why is Mycobacteria so resistant to sterilization?
mycolic acid in their thick cell wall helps deter disinfectants
How does moist heat work as sterilization?
the water and high temperature denature proteins in the cell wall of bacteria by breaking the intramolecular bond between 2 proteins
How do autoclaves sterilize? What is it useful in sterilizing?
carries out industrial sterilization using elevated temperature and pressure in relation to ambient pressure and/or temperature (can reach 121 degrees C in 15 mins)
heat stable liquids, objects (NOT plastic)
How does dry heat compare to moist heat? Incineration?
DRY HEAT: must get hotter and run longer than moist heat and is limited to inanimate heat-resistant objects
INCINERATION: fast, but expensive, done until completely oxidized; useful in elimination of pathogen-contaminated materials like bandages, carcasses, and tissues
How does the radiant energy spectrum work in sterilization?
< 300 nm has bactericidal effects by disrupting the cell wall
How does UV light have bacteriocidal effects? How is this repaired?
UV light causes thymine to dimerize and distort the DNA molecule
endonuclease can cut out the region with the thymine dimer, allowing DNA polymerase to repair the missing part of the DNA and ligase is able to come in a seal the old strand to the repaired portion
How does ionizing radiation work for sterilization? How is it useful?
X-rays and gamma rays will break down water into oxygen and hydroxyl radicals that will interact with macromolecules and cause disruption of covalent bonds
not very practical, but can sterilize inanimate, heat sensitive materials like syringes and catheters
How can liquid filtration work for sterilization?
if a heat-sensitive liquid is poured over a filter membrane with pores <0.2 microns, most bacteria will be filtered out since the smallest dimension on average is 0.5 microns
What are 4 types of air filtration used for sterilization?
- HEPA = high efficiency particulate airt filter = 99.999% of 0.12 micron particles
- face masks
- sterile hoods
- room air filters
How do Class II biosafety hoods utilize HEPA?
HEPA filter is places at the top of the hood and it filters air within the work space, allowing air to flow into the face opening to protect the user and keep the air in the cabinet filtered and recirculated/exhausted
What are 3 types of alkylating agents used for sterilization? How do they work?
formaldehyde (formalin), glutaraldehyde, ethylene oxide (esp. plastics that cannot be autoclaved)
they are extremely reactive with carboxyl, hydroxyl, and sulfhydryl groups of proteins, they will add a hydroxyl, methyl, or ethyl groups or cross-link reactive groups
How does sonication act in sterilization?
probe vibrates at 9000 cycles/s, causing bubbles to form in a liquid and bombard bacterial cells and lyse them
For which objects is sterilization reserved for?
inanimate objects
Why are autoclaves so efficient for sterilization?
provides efficient transfer of latent heat from water to an object
