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Aseptic technique

You will be expected to employ aseptic technique throughout this course. Here we describe aseptic technique, how to apply aseptic technique in our laboratory, and why it is important.

The phrase "aseptic technique" applies to a wide range of practices that minimize the risk of unintentional contamination by molds, bacteria, etc. For our studies we need to ensure that the only organisms inhabiting our agar plates and broth tubes are the bacteria that we intended to grow there. As we work with our cultures we will employ media that are specifically formulated to support the growth of bacteria. Our media will not only grow the bacteria that you put on the plate, but also bacteria and molds carried on dust particles, flakes of skin, lint from your clothes, and from pipet tips, inoculating loops, anything coming into contact with your cultures that is not sterile.

Best practices

To avoid contaminating your cultures please plan to apply the best practices outlined below.

  • Keep your work area clean and uncluttered
  • Sterilize all media before use, soon after their preparation
  • Learn and practice proper use of a sterile cabinet (laminar flow hood)
  • Use only sterile glass or plastic disposable pipets, tubes, plates, etc.
  • Flame-sterilize all inoculating loops and needles
  • Wait until you are ready to complete the procedure before opening the lid of an agar plate or remove a closure from a tube or bottle
  • Unless you are working in a sterile cabinet, do not take a lid or closure off and set it down on the bench; if you are working in a sterile cabinet and need to set a lid or cap down, place it on the surface with opening down; do not reach over an open plate or container
  • Work quickly. Open just enough, and for just enough time, in order to do what you have to do, then put the closure back immediately. For some procedures you will be asked to flame the edges of a closure, tube or bottle before putting the top back on.
  • Pay attention to what you and others around you are doing. Avoid talking, whistling, etc. when you have a container open to avoid contamination from aerosols.

Why should you learn aseptic technique?

  • If you plan a career in research, consider that for laboratory work in the biological sciences it is often critical to avoid contamination of samples, cultures, etc., ruining your experiment
  • If you plan a career in health professions, protecting patients from infection will be a major concern of yours
  • If a family member becomes immunocompromised, if you have children who experience the inevitable cuts, scrapes, etc., encounter someone with a serious injury in which the skin is broken, or even plan to grow old and suffer the usual decline in the ability to fight off infection, you should be well aware of the risk of sepsis and how to avoid it.

Created by David R. Caprette, Teaching Professor, Rice University ( 21 Dec 16 for the course BIOC 318, Laboratory Studies in Microbiology. Please feel free to copy and/or modify these materials for use in your own academic or other nonprofit program. If you don't mind letting me know of such intentions I'll be happy to hear from you.
Last updated 21 Dec 16