when are sterile techniques important
Sterile techniques are extremely important when maintaining cell cultures.
how do you store cell culture
Most fungal, bacterial and mammalian cell cultures can be stored at -80ºC when not in use.
what is a hemocytometer
The hemocytometer is the most common tool used for determining a cell culture concentration.
what do we need to do prior to using a hemocytometer
Since cell cultures are typically in the range of millions or billions of cells per millimetres, the culture must be serially diluted to reduce the concentration to a countable range on the hemocytometer.
what are sterile techniques
Sterile or aseptic technique is a set of procedures used when one works with cell cultures in order to avoid contamination of the culture with unwanted microorganisms or other material. It also protects you, your work surroundings, and your colleagues from contamination with possible harmful microorganisms.
You should always treat any cell culture as if it contains potentially harmful organisms. Why? (3 reasons)
- You could accidentally introduced a harmful microbe as a contaminant, and this can grow with the intend organism. Large numbers can arise quickly
- Previously harmless microbes may alter their characteristics as a result of gene exchange or mutation and become harmful.
- Not everyone exposed to a harmful microbe may become ill. Some people are more susceptible to infection than others, and they could be harmed.
when is something sterile
- To be truly sterile, an object cannot contain any living thing
- Objects are sterile only if they have been treated to kill all microorganisms
what makes something not sterile
- A sterile object that comes into contact with any non-sterile object, however briefly, is no longer sterile
is air sterile
- Air is not sterile
how do we sterilize solutions and containers
All solutions and containers to be used for sterile technique are first autoclaved (high-pressure steam sterilization), irradiated or sterilized by other proven methods of sterilization
how do we transfer sterile materials
Thereafter, sterile tools must be used to transfer the materials in a manner that minimizes exposure to air and avoids contact with non-sterile objects. Such materials can only be used once for transferring cells, then must be discarded or re-sterilized.
What should we be aware of with breathing in sterile labs
Do not breathe directly over open sterile containers. Minimize air currents wherever possible in the immediate work area by closing doors or windows and avoiding unnecessary walking in the lab
what does a bunsen do for sterility
The mouths of all open containers should be passed briefly through a bunsen burner flame. Do not hold the container continuously over the flame. This kills microbes on the outer surface, and creates a positive pressure that pushes air and any contaminants away from the culture.
what should you do with sterile lid
Lids of sterile containers should be removed for the shortest-time possible. They must not be placed on, or come into contact with, a non-sterile surface for the duration of their removal.
what should you do with sterile, caps, lids and plates you just removed
Sterile caps, lids and cotton plugs from culture containers must not be placed on the bench; they should be removed and help open side down
how should you hold open containers
Whenever possible, open containers should be held at a sharp angle to prevent contaminants from falling in
what should you always wear when handling cultures
Always wear disposable gloves when handling cultures
How should you mix sterile tubes
To avoid contamination from fine droplets of culture suspensions when mixing by inversion, use covered tubes during these procedures
how should you never cover an open culture
Never cover an open culture container with a finger or thumb, even if gloved
how should you pour solutions into culture containers
Pour solutions slowly into culture containers, keeping differences in height between the supply and receiver containers to a minimum to avoid spills or splashes
how should you discharge a pipette
Slowly discharge a pipette against the inner wall of the receiving container to prevent slashing or overflows
How should you dispose of contaminated materials
All contaminated materials must be disposed of according to federal and provincial regulations, and safety guidelines established by the University’s Occupational Health and Safety Office
where do you put disposable materials
Disposable materials such as gloves, pipette tips, paper towels, etc. Must be placed in an orange autoclave bag, not the ordinary garbage.
where does broken glassware go
Broken glassware and used pipettes must go into the labeled glass waste containers.
