RODAC Plates and Their use in Pharmaceuticals : Pharmaguideline

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RODAC Plates and Their use in Pharmaceuticals

RODAC plates are used to take a sample from any surface to determine the microbial load on the surface. It is an alternate method for swab sampling.
RODAC is an abbreviation of Replicate Organism Detection and Counting. It is usually used for surface sample testing. It is an agar, poured in a contact plate and pressed flat so that the organisms can stick to its medium. It should also be refrigerated at a 40 degree Fahrenheit and make sure that it does not get frozen. The agar is 50 millimeters in diameter and is also in the shape of a dome.

When it is made it should have a good arched surface so it can make proper contact otherwise, it will not work. You can buy the contact plates commercially but, it would be a disadvantage due to the residue left behind. You can also make the contact plates in your house. Making the contact plate in your house is less expensive and more advantageous since you don't need to process anything after the sampling and you may have a good recovery. It has specific maintenance and procedures that need to be followed to get the right outcome. For those who wish to make it in your house, you should be aware of what is needed and how it is handled.

Types of RODAC

There are three standard types of RODAC, and each has a different purpose.
The first type of RODAC is BPA (Baird Parker Agar). It is used to determine the amount of Staphylococcus aureus. Staphylococcus aureus is a bacterium that is a known cause for skin, wound, and internal organ infections. It also forms toxins that may cause food poisoning.

The second of RODAC is VRBGA (Violet Red Bile Glucose Agar), which is used to determine the amount of E (Enterobacteriaceae). It is a bacteria that includes Salmonella and Klebsiella.

The third type of RODAC TSA (Tryptone Soya Agar) that determines the total amount of micro-organisms (general hygienic state). Compared to the PSA (Plate Count Agar), which is also a standard method but not a selective medium, TSA is more abundant in nutrients. It also contains Tween 80 and Lecithin.

What are RODAC Plates use in Pharmaceuticals

Contact plates are usually used to assure the cleanliness of the cleanrooms, laboratory, etc.. It is to ensure the biosafety to reduce the potential for contamination by observing cleanliness and in diminishing the probability of contamination in the process of it. For example, there is an assurance of cleanliness in cleanrooms because they have an environmental monitoring program. The program evaluates the cleanliness and the effectiveness of disinfecting the environment for air contamination and surface contamination.

There are also two methods on how they examine the air and surface cleanliness. The first method is using an active air sampler (CFU/m3) for air and Contact plate (CFU/25 cm2) for the surface, also known as RODAC. The second method uses a Settle plate (CFU/90 mm over “×” time) for air and Swab (CFU/surface) for the surface.

In conclusion, RODAC is a common sample type made of agar and is used in pharmaceuticals to determine the cleanliness. It is to know the number of microbial colonies and also in their relative position. If made well, using RODAC to identify the colonies of bacteria can help us know how to sterilize and keep the cleanrooms, laboratory, etc. clean and clear from critical illnesses.

Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
.moc.enilediugamrahp@ofni :liamENeed Help: Ask Question

3 comments: Post Yours! Read Comment Policy ▼

  1. Why we use polysorbate 80 and lecithin in scda media plate

  2. Why 25cm², and not 55 mm diameter?
    Which standard is involved?


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