Monitoring Hygiene with Dipslides: A Step-by-Step Guide for Bacterial Testing

Dipslides are frequently used to check the hygiene of surfaces, equipment, and products. They can also be used to monitor bacterial load in cooling water, process water, swimming pools, and wellness resorts. They help you comply with standards such as NEN-ISO 17381 and are also suitable for checking stable hygiene or monitoring metalworking fluids. In this work instruction, we will explain step-by-step how to correctly use dipslides so you can easily monitor the microbiological condition of surfaces and liquids yourself.

Choose the right dipslides for the test you want to perform

There are many different types of dipslides available. To select the correct type, it is important to know which type of microorganism you want to test for. Some dipslides have different culture media on each side, allowing you to do two different tests with one dipslide. An example of this is are dipslides with a general growth medium on one side for total microbial count (plate count agar) and on the other side for fungi or, for example, enterobacteria (VRBGA).

Dipslides often have a shelf life of several months. Store the dipslides according to the instructions on the packaging. Usually, a clean environment at a constant temperature between 8 and 15°C is sufficient. Make sure not to exceed the expiration date printed on the package..

Prepare your sampling plan and strategy for the hygiene control

Think in advance about which surfaces or liquids you want to test. Create a clear sampling form where each sampling point has a unique identification. This keeps your investigation organized and ensures traceable results.

Work hygienically to prevent contamination

From this point on, ensure you work hygienically by maintaining a clean workspace, disinfecting your hands, and preferably wearing a clean lab coat. If desired, use sterile gloves. The goal of these hygiene measures is to prevent false results caused by unwanted contamination of surfaces or your test materials.

Use the dipslide correctly for reliable results

Before taking a sample with the dipslide, carefully remove it from its protective cover. From this moment, avoid coughing, talking, or deep breathing over the surface or the culture medium to prevent contamination.

When sampling with a dipslide, press the culture medium onto the surface for about 5 seconds. Remember that your dipslide has two sides, which can both be pressed onto the surface. If you use the dipslide to check the hygiene of a liquid, immerse the dipslide in the liquid for a few seconds.

Immediately after sampling, place the dipslide back in the protective cover. Be careful not to touch the agar surface. When this dipslide in the cover, this usually protects the dipslide securely.

After sampling, clean the surface where you just pressed the dipslide, as a small amount of agar medium may remain.

Incubating dipslides: not all dipslides require incubation at the same temperature

After sampling, place the closed dipslides upright in the incubator. The temperature and duration needed for incubating your dipslides can often be obtained from your supplier or may be listed on the packaging. If you have multiple dipslides that require different incubation temperatures, place them in separate incubators.

Reading and recording the results

Once the dipslides have been incubated as instructed, remove them from the incubator and assess colony growth by comparing the grown culture medium to the corresponding reference card. Make sure to carefully interpret the results of your bacterial test. This prevents unnecessary alarm about hygiene issues or underestimation of risks. By regularly hygiene tests with dipslides and structured documenting, you can identify trends and evaluate the impact of changes in your process.

If you want to know more about the dipslides we can supply, please feel free to request our current overview.

If, despite these instructions, you would prefer us to carry out the hygiene checks on your site in The Netherlands or Belgium, please feel free to contact us to discuss the options.