Cross Contamination Prevention in Microbiology Laboratory

As we have to work with unseen organisms, cross-contamination doubles the trouble in a microbiology lab. So, let's have a look at how important it is to prevent such contamination.

What is cross-contamination?

Simply, it is an alteration of the original microbes present in a sample with other external sources. In most of the cases, we introduce new ones from another, changing the counts and microbial diversity. Some common sources of contamination are other samples in the lab, the instruments and equipment we use, and the person doing the test.

What are the negative consequences of it?

It will affect in two different ways,

👉The microbiologist may be exposed to harmful microbes 

Usually, analysts adapt their settings according to the bio-safety level of the microbe they are handling. However, in situations like cross-contamination, they can be infected with pathogenic organisms that cause serious health problems.

👉Reduce the test accuracy by generating false results

As a result of the alterations, we will end up with different counts than the real ones in the enumeration methods. It may be a higher or lower count than the uncontaminated state.  Moreover, it will lead to false positives in detection (presence/absence) methods.

How to prevent it?

👉Sterilization of equipment

Although many sterilization methods are available, tailored to the properties of each material, the most widely used in microbiology laboratories is autoclaving. Sterilization with the appropriate time-temperature combination destroys microbes from glassware and other lab equipment. 

It is mandatory to ensure the effectiveness of the sterilization process to eliminate possible contamination.

👉Environmental controls

Cleanliness of the laboratory environment reduces the introduction of microbes present in the surroundings. To reduce microbial contamination coming from the environment, air filtration ( using HEPA filters) and UV Irradiation are commonly used in testing areas, where sanitizing agents like 70% alcohol are used on the working bench and other surfaces.

👉Personal hygiene and safety precautions

As a microbiologist, it is a must to maintain good hygiene practices, where hand washing and sanitation play a major role. This is because it prevents contamination that may happen during sample handling and testing.   On the other hand, safety measures protect the person from getting contaminated by the microbes in the samples. 

Therefore, being aware of good laboratory practices, bio-safety levels (BSL 1 to BSL 4), PPE, and other safety requirements for each category is essential when working in a microbiology laboratory.

👉Aseptic Techniques

From the beginning to the end of a test, aseptic techniques must be used to avoid contamination. Sample preparation, inoculation, transferring, culture media handling, and the use of microbial cultures need to be done in a careful manner with proper technique, especially when using inoculation loops, plates, pipettes, and other equipment.

How to maintain the preventive measures?

Contamination prevention may become useless if it is not continuously assessed. So, quality assurance in the laboratory is the way to verify that preventive actions are accurate and in place all the time. Routine monitoring, documentation, frequent auditing, and staff training are some key features of that.

In conclusion, a deep understanding of cross-contamination will enhance the accuracy and reliability of the work while developing your competence and confidence.