Nine Safe Practices for the Microbiology Laboratory
By Daniel E. James
Treat all microorganisms as potential pathogens. While the majority of microorganisms are not
pathogenic to humans and have never been
shown to cause illness, under unusual
circumstances a few microorganisms that are
not normally pathogenic can act as
pathogens. Treat all microorganisms—especially
unknown cultures—as if they were pathogenic.
A student who has a compromised immune
system or has had a recent extended illness
should talk with the instructor before
working in the microbiology laboratory.
Sterilize equipment and materials. All
materials, media, tubes, plates, loops, needles, pipetes, and other
items used for culturing microorganisms should be sterilized by
autoclaving. Otherwise, use commercially sterilized products.
Understand the operation and safe use of all equipment and materials
needed for the laboratory.
Disinfect work areas before and after use. Use a disinfectant, such as a 10%
bleach or 70% ethanol solution, to wipe down benches and work areas
both before and after working with cultures. Also be aware of the
possible dangers of the disinfectant, as 70% ethanol can catch fire
around open flame or high heat sources. Bleach, if spilled, can ruin
your clothing. Either alcohol or bleach can be dangerous if splashed
in the eyes. Students should know where the nearest eyewash station
and sink are located.
Wash your hands. Use a disinfectant soap to
wash your hands before and after working with microorganisms.
Nondisinfectant soap will remove surface bacteria and can be used if
disinfectant soap is not available. Gloves may be worn as extra
protection.
Never pipette by mouth. Use pipette bulbs or
pipetting devices for the aspiration and dispensing of liquid
cultures.
Do not eat or drink in the lab, nor store food in areas where microorganisms are stored. Never eat or drink in the
laboratory while working with microorganisms. Keep your fingers out
of your mouth, and wash your hands before and after the laboratory
activity. Cover any cuts on your hands with a bandage. Gloves may be
worn as extra protection.
Label everything clearly. All cultures,
chemicals, disinfectant, and media should be clearly and securely
labeled with their names and dates. If they are hazardous, label
them with proper warning and hazardous information.
Autoclave or disinfect all waste material. All items to be discarded after a class, such as culture tubes,
culture plates, swabs, toothpicks, wipes, disposable transfer
needles, and gloves, should be placed in a biohazard autoclave bag
and autoclaved 30 to 40 minutes at 121° C at 20 pounds of pressure.
If no autoclave is available and you are not working with pathogens,
the materials can be covered with a 10% bleach solution and allowed
to soak for at least 1 to 2 hours.
Clean up spills with care. Cover any spills
or broken culture tubes with a 70% ethanol or 10% bleach solution;
then cover with paper towels. After allowing the spill to sit with
the disinfectant for a short time, carefully clean up and place the
materials in a biohazard autoclave bag to be autoclaved. Wash the
area again with disinfectant. Never pick up glass fragments
with your fingers or stick your fingers into the culture itself;
instead, use a brush and dustpan. If working with
animal or plant pathogens, keep the area clear and notify your
instructor
