level 2 (BSL‐2)Appropriate for handling moderate‐risk agents (RG‐2). These include agents associated with human disease, but for which immunization or antibiotic treatment is available; examples include Salmonella and Measles virus.All precautions for BSL‐1 are observed, plus doors must be lockable and marked with biohazard signs, eyewash station is available, air does not recirculate to non‐laboratory areas, and autoclave is available.Special work areas (e.g., biosafety cabinets) should be assigned for activities that might generate aerosols or splashing and for handling large volume or high concentration of organisms.
Biosafety level 3 (BSL‐3)Appropriate for handling agents that may cause serious and potentially lethal infections (RG‐3). These include agents that are transmittable by aerosols. Examples of these agents are Mycobacterium tuberculosis and St. Louis encephalitis virus.All precautions for BSL‐2 are observed plus separate facility or zone with double door entry; inward only airflow with 10–12 air changes/hour; water‐resistant walls, floors, and ceilings; filtered vacuum lines; and respiratory protection may be required.
Biosafety level 4 (BSL‐4)Appropriate for handling exotic agents (RG‐4) that (a) pose high risk of life‐threatening diseases, (b) are transmittable by infectious aerosols, and (c) for which no treatment is available. An example of these agents is Ebola virus.All precautions for BSL‐3 are observed plus single‐pass dedicated air system; walls, ceilings, and floors create an internal seal; all liquid effluent and solid waste are decontaminated; entry doors cannot be opened simultaneously; communication system; emergency generator, positive pressure personnel suit, and showering upon exit are required.
Note: Food microbiology laboratories that accommodate pathogen work are classified as BSL‐2.
Decontamination and Waste Disposal
Contaminated but reusable laboratory utensils and glassware should be decontaminated before cleaning. Chemical disinfection or autoclaving are often used in this case. Contaminated disposable items (e.g., disposable gloves, pipettes, and agar plates) should be placed in designated biohazard boxes with liners. Disposal of these biohazard boxes should be managed by a professional service, which may subject these items to incineration or other validated decontamination method.
PERSONAL SAFETY IN THE LABORATORY
It is important that students become familiar with the personal protective equipment required for working in a microbiology laboratory as well as safety‐associated procedures and etiquette.
Personal Protective Equipment
Personal protective equipment (PPE) is needed to protect against physical, chemical, and biological laboratory hazards. Availability of this equipment is important but adequate training on how to use it is equally important. The following is a partial list of PPE, but others may be needed:
Safety glasses: These should be cleaned and sanitized before and after use. Alcohol wipes may be adequate for the sanitization.
Laboratory gowns or coats: These should be used and kept in the laboratory.
Face masks and face shields: Masks and shields protect against splashes and aerosolized droplets and particles. These are also essential to prevent the spread of infectious airborne agents.
Gloves: Use of disposable gloves is essential for most laboratory activities.
Observing Personal Safety
Appropriate attire. Wear appropriate clothing for laboratory work. Closed‐toe shoes must be worn during each laboratory period. No sandals, open‐toe shoes, or bare feet are permitted. Shorts may be disallowed.
Winter coats and backpacks are stored away from the bench. Keep these items at a safe distance from the laboratory bench and preferably outside of the laboratory. Coat hangers, cupboards, or preferably lockers should be used to store these items temporarily while students are working in the laboratory.
Items brought to the bench are subject to contamination; these should be kept to a minimum. Keep away all books, notebooks, calculators, laptop computers, and similar items. Technically, two sheets of paper and a pencil are all that need to be brought to the bench. One of these papers contains the laboratory exercise summary, outline, or flow chart, and other is used for recording data. It is advisable that these two sheets are kept in a transparent plastic sleeve that can be sanitized at the end of the exercise.
Mobile phones should not be handled during the laboratory period.
Laboratory coat. It is mandatory that a laboratory coat or similar protective covering is worn during each laboratory period. The coat must have either buttons or a zipper. The laboratory coat should be labeled with the student’s name and be kept completely buttoned or zipped for the duration of the laboratory period. After completing the work, coats should be kept in the laboratory. The instructor will point out appropriate coat storage, if available. Before coats are removed from the laboratory, they should be properly decontaminated; this can be accomplished by autoclaving.
Eye protection. Safety goggles should be worn all the time in the laboratory.
Washing hands. Washing hands minimizes or prevents the transfer of organisms between the analyst and the food to be analyzed and vice versa. Hands should be washed before starting any exercise (to avoid contaminating items being analyzed) and after the exercise (to prevent spreading contaminants outside the laboratory).
Use disposable gloves. Even though disposable gloves may not be required for some experiments, it is advisable to wear these gloves for all activities in the laboratory. Analysts who have allergies to latex should wear gloves made of alternative materials (e.g., nitrile rubber). Once the work is completed, the gloves should be disposed of properly in the appropriate biohazard containers. Analysts should never leave the laboratory with gloves on. It is a sign of great carelessness when analysts are seen in hallways or elevators wearing disposable gloves. This can also be the cause of serious cross‐contamination on non‐laboratory surfaces, such as doorknobs.
Clean and sanitize the laboratory bench. Use disinfectant and paper towels to wipe the laboratory bench both before and after any exercise. These paper towels should be disposed of in the regular trash, unless directed otherwise by the instructor.
Never begin laboratory work without the prior permission of the laboratory instructor or supervisor. Generally, students are not allowed to work until after the instructor’s presentation on the day’s activities. If arriving early, the student may use this time to change into appropriate dress, review the exercises to be completed, inspect the laboratory for locations of needed equipment, and similar activities.
Eating or drinking in the laboratory is forbidden. The laboratory environment is not an appropriate place for eating or drinking. In fact, any activity that might involve putting something into the mouth, (e.g., chewing gum, chewing tobacco, using a throat lozenge, smoking, habitually chewing on a pencil) may provide an opportunity for a pathogen to infect the analyst.
Applying cosmetics in the laboratory, including lip balm or lotion, is not allowed. Anything that is applied may trap contaminants on the skin or introduce contaminants into the laboratory environment. Insertion of contact lenses is not permitted in the laboratory.
Avoid
