1.1: Laboratory Safety
- Introduction to lab safety rules and student conduct in a microbiology lab.
- Discuss Potential Safety Hazards: Biosafety Levels, Incinerators and Bunsen Burners, Proper Biohazard Disposal, and Handling and Storing Microbes.
- Demonstrate good aseptic technique.
Microbiology Laboratory Safety
Working in a microbiology lab potentially exposes personnel to certain hazards. Improper handling of microbes, lab equipment, and chemical reagents may result in injury or infection. By reading the following policies, you will learn how to maintain a safe working environment in a microbiology laboratory.
The risks associated with microbiology lab work are determined by the C enter for D isease C ontrol (CDC) and N ational I nstitutes of H ealth (NIH). By studying pathogens, like Haemophilus influenzae , these organizations determine the control required to work with a specific microbe and the corresponding lab cleanliness/aseptic measures. The CDC and NIH have created a microbe classification system based on the microbe's transmission, disease severity, and research prospects. This system is called the B iological S afety L evels or BSLs and it has four levels, BSL1 through BSL4. In this lab, you will be working exclusively with BSL1 microbes, but it is important to understand all aspects of each BSL level.
Figure 1. BSL1 lab spaces require basic safety measures as the biological agents present are typically not able to cause disease in healthy individuals. Washing hands, wearing proper PPE, properly disposing of microbes, and cleaning the lab space daily are required standards for BSL1 research.
| Risk Level | |||
| BSL1 | BSL2 | BSL3 | BSL4 |
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| PPE Requirements | |||
| BSL1 | BSL2 | BSL3 | BSL4 |
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| Facility Requirements | |||
| BSL1 | BSL2 | BSL3 | BSL4 |
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Microbiology Laboratory Safety Rules
The following rules must be followed at all times when working in a microbiology lab.
Student Conduct
- No eating, drinking, chewing gum, or smoking in the lab space. All food and liquid must be left outside of the lab in designated areas.
- Do not apply cosmetics in the lab space.
- Do not handle contact lenses in the lab space. Please wear prescription glasses to the lab. If you need to change or handle contact lenses, you must thoroughly wash your hands, leave the lab space, and then fix your contacts.
- NO CELL PHONES. Do not use your phones during lab. Cell phones must be turned off and kept in your personal bags.
- Do not remove any microbes, biological agents, chemical reagents, lab equipment, or any other microbiology lab item from the lab space. Everything must stay in the lab.
- Be respectful. Absolutely no rough-housing, running, or throwing in the lab space. These movements increase the chance of injury or damaging the lab space and reagents.
- Come to lab prepared. This includes: wearing proper PPE (see Lab Rules below), reading your lab manual, completing lab quizzes, not being late to lab, and working carefully. Always take your time and work slowly and carefully through our experiments.
- Students who are immunocompromised, pregnant, or become pregnant must inform the instructor so additional safety measures can be taken.
Lab Rules
1. All students will be required to wear BSL1 PPE. This includes:
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Protective Clothing: long pants, shirts with sleeves, and closed-toed shoes.
- Lab coats are available for student use.
- Sandals, open-toed shoes, or sleeveless shirts or shirts with spaghetti straps will not be allowed.
- Dresses, skirts, and shorts must reach below the knee.
- Gloves.
- Protective Eye Wear.
- Long hair must be tied back.
- Book bags, purses, and other personal items will be kept away from the work benches.
2. Students will be taught and must know the location of the:
- Fume Hood: for work with volatile chemicals and stains.
- First Aid Kit
- Fire Blanket
- Fire Extinguisher
- Chemical Shower/Safety Shower
- Eye Wash Station
- Report any injuries to your instructor immediately. Make sure all cuts, scrapes, and other open wounds are sterilized and covered before entering the lab space.
3. Students must wash hands when they enter the lab and any time they leave and re-enter the lab. More information on handwashing can be found in the "1.2 Effectiveness of Handwashing" section of this manual.
4. Students are required to keep the lab space clean.
- Clean bench tops with 10% bleach and paper towels before and after experiments.
- Microbes, biological agents, chemical reagents, microscope slides, used gloves, and other materials must be disposed of properly. See "Laboratory Disposal and Equipment Rules" below.
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If there is a spill, tell the instructor immediately.
- Paper towels should be soaked with undiluted bleach, placed over the spill, and left for 20 minutes.
- Put all chemical reagents and non-perishable items (sharpies, inoculation loops, lens paper, etc.) back in their labeled/designated area at the end of lab.
Figure 2. The CDC provides universal guidelines for laboratory safety. Remember that anything you touch in lab has the potential to be transferred to other surfaces. Wash your hands, wear gloves, and leave personal items outside of the lab space.
Laboratory Disposal and Equipment Rules
Proper disposal of microbial agents and chemical reagents is key to personal and public safety in a microbiology lab. We will use biohazard bins, sharps containers, and broken glass containers to dispose of used materials. BSL1 biohazardous material disposed of in these three containers will be autoclaved (heat sterilized) before disposal with normal trash.
1. Biohazard Bin
- Used gloves, cotton swabs, petri dishes, and other lab materials that have come into direct contact with microbes and other biological agents are disposed of in the biohazard bin.
- Microscope slides DO NOT go in the biohazard bin.
- Paper towels that have directly touched microbes or a microbial spill go in the biohazard bins.
- Paper towels that have NOT directly touched microbes ( ie, washing hands, wiping down the work area) may go in the normal trash.
2. Sharps Container
- Self-made microscope slides are disposed of in the hard-plastic sharps container.
- Broken microscope slides DO NOT go in the sharps container.
3. Broken Glass Container
- If you break glass, tell your instructor immediately.
- Do not clean broken glass with your hands.
- Broken microscope slides must be disposed of in the broken glass container. This container should have a plaster liner inside.
To maintain a sterile working environment, students will work with incinerators, petri dishes, and parafilm. Read the following rules on how to safely and effectively use these materials/equipment.
1. Incinerators and Bunsen Burners
- We will not use Bunsen burners. There will be no open flame during lab, but students should still have their hair tied back and be wearing proper PPE.
- Incinerators will be used to sterilize inoculation loops and needles.
- Never touch the exterior of the incinerator. It can cause burns.
- Leave your inoculation loop or needle in the incinerator for 10 seconds. The loop or needle should glow red/orange and the handle may become warm to the touch. (Allow the loop or needle to cool before collecting bacteria or you risk killing/damaging the cells).
- Never leave your loop or needle in the incinerator unattended. The metal can melt or burn you if left unattended.
2. Petri Dishes and Parafilm
- We will grow microbes on plastic petri dishes wrapped in para-film.
- Petri dishes serve as sterile containers with lids that we can use for solid growth media.
- Parafilm is used to enclose the petri dish once microbes have been inoculated.
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Parafilm is a stretchy plastic similar to kitchen plastic wrap that:
- Seals your sample
- Prevents spills
- Prevents contamination
- Prevents exposure or inhalation of the microbes
- Never open a petri dish that has been wrapped with parafilm. Never touch, inhale, or consume microbes.
Healthcare-Associated Infections
H ealthcare- a ssociated i nfections or HAIs are any infection that develops in a healthcare setting. HAIs are a serious concern for anyone involved in healthcare and can affect: patients and their families, doctors, surgeons, nurses, and any other personnel involved. HAIs spread rapidly. 1 in every 31 hospital patients will develop at least 1 HAI per day in America alone. (CDC, 2024)
The most common HAIs are infections related to indwelling medical devices. For example, urinary tract infections caused by catheters and pneumonia caused by ventilators would both be classified as HAIs. HAIs pose significant risks to immunocompromised patients and older patients. These patients have decreased natural immunities and will likely develop long-term complications, prolonged hospital stays, or death in severe cases. No matter a person’s age or health, HAIs are spread through the chain of infection. The chain of infection is a 6-step process by which a microbe is spread between hosts and an infection/disease develops.
Chain of Infection:
1. Causative Agent: microbes like bacteria or viruses.
2. Host/Reservoir: a nurse, patient, or other individual in a healthcare setting.
3. Portal of Exit: sneezing, coughing, vomiting, and other bodily excretions.
4. Method of Transmission: may be direct contact or indirect spread.
5. Portal of Entry: nose, mouth, eyes, and other orifices.
6. Susceptible Host: anyone who contracts the microbe.
The chain of infection can be broken or inhibited by following proper laboratory safety procedures, like the ones presented in this lab manual. Beyond lab safety, HAIs can be decreased by maintaining personal health. A healthy diet, sufficient sleep, and vaccinations are also methods that break the chain of infection. Updated vaccinations are a key step to decreasing HAIs, specifically respiratory HAIs. Respiratory related HAIs (Flu, COVID-19, RSV) typically see an increase in infection rate starting in October and lasting throughout the winter season. Yearly vaccinations have proven vital to decreasing their transmission. The 2023-2024 COVID-19 vaccine helped decrease COVID-19 related hospitalizations by 50% and decreased 58% of COVID-19 associated illnesses. (CDC, 2024)
Attributions
"Microbiology Labs II: Aseptic Technique and Transfer of Microorganisms" by Dr. Gary Kaiser , LibreTexts: Biology , Community College of Baltimore County, Catonsville Campus is licensed under CC BY 4.0
"Microbiology Laboratory Manual: Labs, 1.1 Lab Safety" by Dr. Rosanna Hartline , LibreTexts: Biology , West Hills College Lemoore is licensed under CC BY-NC-SA 4.0
"Microbiology Textbook: Chapter 13, Controlling Microbial Growth " by Openstax , Digital ISBN 13: 978-1-947172-23-4 is licensed under CC BY 4.0
"The Introduction to Microbiology: Depth and Breadth of Microbiology" by Marisa Cases , "A remix of OpenStax: Microbiology", Manchester Community College is licensed under CC BY 4.0
"Biosafety in Microbiological and Biomedical Laboratories (BMBL) 6th Edition" by Centers for Disease Control and Prevention , Use of CDC Materials Statement is in the Public Domain
"DOHS: Safety" by National Institutes of Health, Office Management , Use of NIH Materials Statement is in the Public Domain, CC0
"Healthcare-Associated Infections (HAIs): About HAIs" by Centers for Disease Control and Prevention , Use of CDC Materials Statement is in the Public Domain
"Healthcare-Associated Infections (HAIs): HAIs: Reports and Data" by Centers for Disease Control and Prevention , Use of CDC Materials Statement is in the Public Domain
"Healthcare Worker Vaccination is Important for Respiratory Virus Season 2024" by Centers for Disease Control and Prevention , Use of CDC Materials Statement is in the Public Domain
"Fundamentals of Nursing Textbook: Chapter 10, Infection Control and Prevention" by Openstax , Digital ISBN: 13: 978-1-961584-41-9 is licensed under CC BY 4.0
Image Citations
Figure 1, Modified from:
- "Infographic: Biosafety Lab Levels" by Centers for Disease Control and Prevention , Use of CDC Materials Statement is in the Public Domain, CC0
Figure 2, "What You Work With Can Make You Sick" by Centers for Disease Control and Prevention , Use of CDC Materials Statement , National Center for Emerging and Zoonotic Infectious Diseases Contribution is in the Public Domain