The aseptic technique is used in microbiology to prevent contamination of microorganisms, the testing facility, and personnel. As many common functions of microbiology involve known pathogens or delicate cultures, the importance of using the proper sterilization is paramount.
According to guidelines established by the Center for Disease Control and Prevention, the standard safety procedures for most microbiological applications fall within two basic levels of safety: Biosafety Level 1 and Biosafety Level 2.
BSL 1 is the lowest priority biosafety level covering microbes considered “low-risk.” These tend to pose little to no threat of infection in healthy adults. BSL 1 labs aren’t required to be isolated from other facilities and require only standard microbial safety procedures.
BSL 2 covers laboratories that work with materials associated with diseases, pathogens, and infectious agents. BSL 2 labs carry the same safety standards as BSL 1 labs, but include enhanced safety measures to protect against viral infections, accidental ingestion of agents, and mucous membrane exposures. These standards dictate that personnel must wear appropriate protective equipment as needed, proper warning signs, sink and eyewash safety stations, and a biological safety cabinet (BSC).
To comply with the four different BSLs, microorganisms must be transferred quickly between test tubes, slides, plates, and growth environments in order to avoid accidental contamination. Ensuring sterilization of growth environments and other analysis media through the aseptic technique requires use of a Bunsen burner. Holding the inoculating loop over the flame of the Bunsen burner kills all contaminating organisms when held until the loop glows red-hot for several seconds.
Then, allow the loop to cool before picking up organisms from the inoculum culture without setting it aside or down on the table (which may contaminate the loop). The same procedure can be used to prevent airborne contaminants from entering a test tube via convection currents.
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