Aseptic Technique in the Microbiology Laboratory

What is aseptic technique?

Aseptic techniques are a set of specialized procedures and routine practices used in microbiology laboratories to prevent contamination of samples and cultures throughout the analysis. They are essential for producing accurate and reliable results, as contamination can lead to false or misleading results that could impact research findings and conclusions. Thus, it is really important for every lab personnel to have deep understanding of the principle of the aseptic technique.

Microorganisms are everywhere, including in the laboratory environment. Back to the age of 1860, the aseptic technique was introduced by Joseph Lister as he intended to prevent infection during and after the surgery procedure by using carbolic acid as an antiseptic. He was initially inspired by the microbiological discoveries of Louis Pasteur, which disprove the theory of spontaneous generation. Nowadays, this technique has been implemented in various healthcare settings, research laboratories, food facilities, and microbiology laboratories as a standard precaution to eliminate the risk of contamination.

Principle of aseptic technique

1. Wearing appropriate personal protective equipment (PPE)

PPE is a need when you need to deal with biological or microorganisms. PPE such as gloves, gowns, masks, and eye protection can help prevent the spread of contaminants from the skin or respiratory system from coming to contact with cultures or media. It is important to follow proper PPE protocol and to replace or sterilize PPE between experiments to maintain its effectiveness.

Read more on: Personal protective equipment in laboratory.

2. Using a biological safety cabinet

A biological safety cabinet is a specialized workstation that uses a constant flow of sterile air to create a sterile environment for handling samples and cultures. It can be used to perform aseptic manipulations, such as transferring cultures from the bottle to the petri dish, without the risk of contamination.

3. Cleaning and sterilizing surfaces and equipment

All surfaces and equipment should be cleaned and sterilized before and after use to minimize the risk of contamination. Disinfectants and autoclaves are commonly used for this purpose. Prior to the experiment procedure, all the media, pipette tips, tubes, and bottles need to be sterile to kill unwanted microorganisms that may potentially contaminate the experiment. Spray decontaminant or alcohol on the working bench and wait for 30 seconds before wiping the bench with a clean tissue. Read more on how to achieve effective sterilization.

4. Handling samples and cultures carefully

Samples and cultures should be handled using sterile pipettes and other equipment to minimize the risk of contamination. It is important to avoid touching samples and cultures with bare hands, as the skin is a natural reservoir for microorganisms. If you are required to transfer the culture media, is advisable to use the sterile pipette to transfer the culture media from the bottle to the petri dish and never uncover the bottles, sterile flask, and petri dish throughout this process to prevent microorganisms and airborne contaminants from gaining entry. Furthermore, always flaming the neck of the bottles and tubes before closing them to ensure no microbe could potentially enter the mouth of the vessel and contaminate the culture media.

Furthermore, if you need to transfer culture to a new medium, this procedure needs to carry out in an open lab environment and cannot be operated in a biological safety cabinet. Nevertheless, the Bunsen burner comes in handy to reduce the risk of contamination within this open environment as it draws all the air current upward and reduces the bacteria within its surrounding. All transferring work must be done near the Bunsen burner and the inoculating loop need to be preheated prior to the inoculation process. Keep in mind that you need to carry out this procedure as fast as possible and limit the inner exposure of the sterile inner surface of the petri dish to contamination in the air.

In addition to these specific techniques, it is also important to maintain good general laboratory practices to prevent contamination. This includes keeping the laboratory clean and organized, following proper handling and disposal procedures for hazardous materials, and following good hygiene practices such as washing hands regularly. Maintaining strict aseptic techniques is especially important when working with pathogenic microorganisms, as these could affect the entire experiment.

In these cases, it is essential to follow additional precautions, such as wearing additional layers of PPE and working in a biosafety cabinet or other specialized containment facility. It is also important to be aware of the potential for cross-contamination, which can occur when microorganisms from one sample or culture are transferred to another. This can be prevented by using separate equipment and materials for each sample or culture and by following proper sterilization and decontamination procedures.

By following these aseptic techniques and good general laboratory practices, you can help ensure that your microbiology laboratory is a safe and sterile environment for conducting experiments and producing accurate and reliable results. It is essential to maintain strict aseptic techniques in order to produce high-quality research findings and to ensure the integrity of the scientific process.