Dipslides - All you need to know

Dipslides - All you need to know
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Dipslides - All you need to know

What is a Dipslide?

A dipslide is a means of testing the microbial content of liquids. This is a common method of monitoring and measuring microbial activity within many systems and commonly cooling systems. Usually, the use of a dipslide is the first line of defence for the testing of microbial issues that could be caused to manufacturers and machine shop fluid systems. 

Dipslides consist of a plastic barrier which bears a sterile culture medium which can be dipped into the liquid being sampled. The resulting microbial colonies are estimated by reference to a chart. 

Dipslides are usually incubated for 48 hours after use and any subsequent bacteria in the sample water will grow and form colonies.

 

Types of Dipslides:

There are several types of dipslides and each dipslide is designed to test for specific types of bacteria.

  • TTC/TTC Dipslides - These are general purpose dipslides that implement triphenyl tetrazolium chloride to produce a red coloration when reacting with living cells. Typically used in water testing.
  • TTC/MALT Dipslides - These dipslides are used to determine total plate count with TTC addition on one side of the carrier and culture yeast and moulds for determination on the MALT side with acidic culture medium. Typical use in industrial waters, food production and other systems with complex water matrices for general hygiene.
  •  TTC/RBS Dipslides (Rose Bengal) - These dipslides use a dual agar, with one carrier side having TTC addition for total plate count and the other side having bengal red as a selective medium for yeast moulds. These dipslides are used for general purposes.
  • TTC/MAC MacConkey Dipslides - These dipslides test for TTC as well as the cultivation of Enterobacteriaceae, with colonies showing up as red spots. MacConckey agar selects for bile tolerant gram negative bacteria found in waters and sewage. Typical uses for these dipsldies are; Poultry, Dairy, Water, Pharmaceutical and Biomedical testing.
  • PDM/TTC Dipslides - These dipslides use a dual agar to test for Pseudomonas one side and with a TTC additive on the other side to determine total plate count. Pseudomonas are commonly tested in heavy industry testing, areas of high corrosion and environmental hygiene.
  • TTC/E.Coli Dipslides - Nutrient agar with TTC allows for enumeration of aerobic bacteria. The E.coli side of the dipslide (darker side) tests for E.coli coliforms and Pseudomonas species bacteria in a single test. These dipslides are ideal for a wide variety of applications such as water testing, pool and spa testing, clean rooms and environmental hygiene.

 

 

How to use a Dipslide:

  1. Firstly, ensure your hands are washed and use suitable protective clothing (gloves).
  2. When using a dipslide it is not required to wear nitrile gloves or wash your hands. However, doing this will limit the risk of contaminating the dipslide.
  3. You can now remove the dipslide by pulling the plastic tab at the top of the dipslide. Take care not to hit the side of the tube with the agar when removing the dipslide.
  4. For surface testing, place the dipslide agar down onto the surface you are testing. Keep the agar applied to the surface you are testing for around 20 seconds. You can then repeat this with the other side of the dipslide (if required).
  5. For fluid testing, you can either place the dipslide directly into the fluid or place into a sample of the fluid you are testing. The agar must be submerged for at least 10 seconds. 
  6. For swab testing, grab a sterile bud and rub it onto the sample being tested and then rub that bud onto the agar of the appropriate dipslide.
  7. After testing, place the dipslide back into the sterile holding tub it was in before removal. Then place into an incubator (temperature is dependent on the type of agar being used). Usually, incubation times for dipslides are between 24-48 hours.
  8. Once incubated, you can then use a chart to do a comparison of the number of dots (colonies). This will then provide you with the CFU/ml or CFU/cm2 measurement.

 

Frequently Asked Questions:

How long should my dipslide be incubated for? - Dipslides are typically incubated at 30C for 48 hours after being dipped into the sample to ensure that the results are accurate. However, please check the stated incubation times of your dipslide depending on what sort of dipslide you are using for testing.

How do you know if a dipslide is angled? - To interpret the results of a dipslide, it is important to note that any colonies that are not colored should still be included in the overall assessment. These colonies can sometimes be difficult to see, but if the dipslide is angled, they can be identified as irregularities on the surface.

What is a dipslide test? - Dipslides are a means of testing the microbial content of liquids, commonly used for measuring and monitoring microbial activity within many systems and cooling systems.

Are dipslides single use or reusable? - All dipslides are single use, after use they are classed as contaminated and should be disposed of properly.

How do I dispose of my dipslides? - Dipslides that have been used need to be incinerated, autoclaved or soaked in disinfectant for several hours before disposal. 

Do I need an incubator to use dipslides? - Whilst it is not a necessity, we recommend the use of an incubator to get the best results from your dipslide tests. This is due to the dipslides requiring a constant and stable temperature to incubate. Without the use of an incubator results may not be accurate from the tests.

For more information on Dipslides or if you have any other questions, please contact us here or call us on 01954233110. Alternatively please use the links below to contact us.

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