Sterilization, Disinfection, and Containment-Kozel Flashcards
What is sterilization?
use of physical or chemical agent to destroy all microbial forms, including spores
What is disinfection?
use of physical or chemical agents to destroy most microbial forms; bacterial spores or other relatively resistant organisms may remain viable
What is antisepsis?
use of chemical agents on skin or other living tissue to inhibit or eliminate microbes; no sporicidal action is implied
What is biocide?
– a general term describing a chemical agent, usually with a broad spectrum, that inactivates microbes
T/F We are using too many disinfectants for healthy people & not enough for sick people.
True.
A tube of disinfectant could be called what?
biocide
What are factors that affect disinfectant potency?
conc’n (higher takes less time to kill)
time (more always better! 15 min to kill spores)
pH
temp (killing doubles with every increased degree centigrade)
presence of extraneous materials to bind or inactivate disinfectant
the type of microorganism you’re trying to kill
Prions Coccidia Mycobacteria Cysts Are these relatively resistant to disinfectants or relatively sensitive?
Relative Resistant
Prions are the most resistant
Lipid Enveloped Viruses Gram + Bacteria Large Non-Enveloped Viruses Fungi Are these relatively resistant or relatively susceptible to disinfectants?
they are sensitive!
Lipid Enveloped Viruses are the most sensitive.
With ethylene oxides & aldehydes what is the MOA for disinfecting?
alkylate & cross link macromolecules, such as proteins, DNA, RNA
Give 3 examples of disinfectants that fall into the class of ethylene oxides & aldehydes.
formaldehyde
glutaraldehyde
ethylene oxide
What is the fcn of formaldehyde?
environmental decontamination
used in gas or liquid form
What is the fcn of glutaraldehydes?
chemical sterilization of equipment
What is the fcn of ethylene oxide?
gaseous sterilization of heat sensitive materials
What is the MOA of oxidizing agents for disinfection?
oxidize proteins
DNA breakage
What are 3 examples of oxidizing agent disinfectants?
ozone
hydrogen peroxide
peracetic acid
What is the fcn of ozone?
disinfection of air systems
What is the fcn of hydrogen peroxide?
cleansing of wounds
disinfection of implants, prostheses
What is the fcn of peracetic acid?
chemical sterilant
What is the MOA of halogens as disinfectants?
oxidize proteins
What are 2 examples of halogen disinfectants? What are their fcns?
iodine-skin disinfection
chlorine-chemical decontamination
What is the MOA of phenolic compounds as disinfectants?
disrupt lipid containing membranes
denatures proteins
What are 2 examples of phenolic compounds as disinfectants?
chlorhexidine
triclosan
What is the fcn of chlorhexidine?
skin disinfection
What is the fcn of triclosan?
antibacterial soaps
innumerable other uses!
What is the MOA of quaternary ammonium compounds?
surfactant-amphoteric properties disrupt membranes
What is an example of a quaternary ammonium compound? What is its exact fcn?
benzalkonium chloride
skin disinfection
hard surface cleaning
Ex: lysol
What is the MOA of alcohols as disinfectants? What is the best example of this?
**denatures proteins
Ex: isopropyl alcohol (70%)
skin decontamination, disinfection
**awesome b/c it has minimal environmental effects, kills vast majority of microbes, and wouldn’t be more effective with a higher conc’n
What are mechanisms of intrinsic resistance of microbes against disinfectants?
it varies!
physiological adaptation-biofilms
Why is it that we should be more careful with how many disinfectants we use with healthy people environments?
b/c there is a potential for cross resistance with antibiotics
What are the mechanisms of acquired resistance against disinfectants?
via plasmids or mutation
- *Inactivation of agents
- *Efflux of Agent
- *Decreased uptake-silver compounds?
What are 3 examples of disinfectants that are inactivated by resistant microbes?
Chlorhexidine
Formaldehyde
Mercurials
What are 2 examples of disinfectants that are effluxed from resistant microbes?
Quaternary ammonium compounds
Chlorhexidine
What is the temp required to kill most pathogenic bacteria?
60 degrees celsius
What is the temp required to kill vegetative forms of all bacteria & fungi?
80 dC
What is the temp required to kill spores of pathogens?
100dC
What is the temp required to kill all bacterial spores?
120dC
Pasteurization occurs at which temp?
72 dC
Boiling happens at what temp?
100dC
Autoclaves work at which temp? Which kills the microbes-the heat or the pressure?
120dC
high temp kills
pressure doesn’t
**steam under pressure
What temp is dry heat used to kill microbes?
180dC
What are 2 forms of radiation that can kill microbes?
UV radiation: sunlight, UV lights
Ionization Radiation: xray & gamm a rays
What is the fcn of UV irradiation to kill microbes?
control of airborne or surface contamination
no penetration of solids-only works on the surfaces of microbes-if anything is covering it-no luck!
What is the fcn of Ionization radiation to kill microbes?
sterilization of small heat-sensitive articles
can be used on plastics
could theoretically be used on food safely to get rid of E coli etc.
Aside from radiation, what is another physical agent to kill microbes?
Filtration
Filter sterilization of heat-labile liquids – no removal of viruses or other small forms from liquids
HEPA filtration of air – quite effective, even for viruses-found in vacuums, ovens etc
T/F UV lights are found in hoods in labs.
True.
What’s the deal with the autoclave?
light door lots of pressure-15lbs worth thermostatic sensor used 10-15 min for larger amounts of liquid steam under pressure! the temp does the killing, not the pressure can be dangerous!
What are some important features of biosafety cabinets?
laminar flow across the front of the cabinet
filters inside
hood is vented into room only if it goes thru a HEPA filter
How would you sterilize packages of surgical dressing?
Autoclave
How would you decontaminate liquids from a research laboratory that contain live viruses?
Bleach or autoclave
How would you decontaminate a thermometer used in a pediatrics clinic?
alcohol
How would you sterilize 50 glass flasks containing bacterial culture media?
autoclave w/ a slow exhaust cycle at the end to bring down the pressure to match the temp of the liquid
How would you sterilize plastic pipettes in their plastic wrappers?
ionizing radiation
How would you dispose of a large quantity of laboratory glassware that has been contaminated with pathogenic fungi-autoclave?
autoclave
How would you sterilize 200 ml of tissue culture media?
filter sterilize it
How would you decontaminate a biosafety hood prior to changing of HEPA filters?
hood w/ toxic gas & another to neutralize it
How would you disinfect skin at the site of a lumbar puncture?
iodine
How would you disinfect skin at the site of a venipuncture?
alcohol
How would you process raw milk to remove potentially pathogenic bacteria?
pasteurization
How would you decontaminate a laboratory bench top after routine use for bacterial culture?
disinfectant that is phenol-based
works on membranes
How many biosafety levels are there? What are the important considerations at BSL-1?
There are 4 levels! 1: high school microbio labs Stuff that doesn’t cause disease Ex: E coli, Staph Basic level of containment Not necessarily separated from general traffic Work conducted on open benches Relies on standard microbiological practices No special primary or secondary barriers
What are the important considerations at BSL-2?
- What you see in a hospital diagnostic lab.
Moderate Risk agents: Hep B, HIV
Laboratory hazard is associated with percutaneous exposure, ingestion, or mucous membrane exposure
Laboratory personnel have specific training and are directed by competent scientists
Access to the laboratory is limited; biohazard warning signs
Extreme precautions taken with sharps
Biological safety cabinet used for procedures that generate splashes or aerosols
Note: Risk is not one of inhalation!
You should use a hood.
What are the important considerations at BSL-3?
- Potential for aerosol transmission. You get it-lethal.
Indigenous or exotic agents with potential for aerosol transmission; disease may have serous or lethal consequences
Laboratory personnel have specific training and are supervised by scientists who are experienced in working with these agents
All procedures involving manipulation of infectious agents are done in a biosafety cabinet or other physical containment devices
The laboratory has special engineering and design features, including security
**Use a really good hood!!! CDC inspected.
What are the important considerations at BSL-4?
- Work with things like Ebola. 4 or 5 in the US
Work done with dangerous and exotic agents that pose a high individual risk of aerosol-transmitted laboratory infections and life-threatening disease
Laboratory staff have specific and extensive training.
Access to laboratory is highly controlled
Facility is isolated and has special engineering and design features to prevent spread outside facility
All activity confined to Class III biological safety cabinets (fully self contained) or Class II cabinets with personnel using positive pressure suits ventilated by a life support system
