What Is Media Fill Testing?

December 15, 2020

Media fill testing is the method of assessing the technique and competency of personnel who manipulate and create compounded sterile preparations. To maintain the purity of samples, compounds and other materials, compounding personnel must be sufficiently skilled at “aseptic manipulation.” This refers to the ability to execute filling, transferring and handling tasks without contaminating the material — known as compounded sterile preparations (CSPs) — at hand.

A media fill test applies a quantitative analysis to this critical skill. This assessment allows a pharmacy to operate with the confidence that sterile compounding is carried out with purity. Further, this test enables management to identify workers who may need additional training. Without regular media fill testing, a facility cannot be certain that proper mixing and handling techniques are being followed consistently. This may lead to contaminated CSP and ultimately patients’ safety risk.

The United States pharmacopeia general chapter <797> (known as “USP <797>”) outlines a guideline for media fill testing requirements and recommendations for facilities. The minimum requirement is testing upon hire — and then an annual revalidation for applications denoted low- and medium-risk, and a twice-annual revalidation for high-risk applications. However, some facilities employ more stringent requirements (as frequently as quarterly or more) to meet their aseptic handling requirements.

The Media Fill Test Process

Media fill tests must be carefully designed and controlled to yield accurate, reliable and repeatable results. Testing material must be carefully handled during preparation to ensure the integrity of the test. It is important to note that one facility may have multiple media fill test procedures per employee for evaluation to all compounding activities routinely expected.

  1. Acquire testing medium. The testing medium will be a microbiological growth medium such as Triptic Soy Broth (TSB) that will reveal whether exposure or contamination occurs during the test.
  2. Choose the time and circumstances of the test. As closely as possible, real-world scenarios and worst case situations must be replicated for testing. If a worker will typically be operating with other personnel in the room, for instance, he or she should not necessarily be tested in a quiet, controlled environment.
  3. Carry out the test. USP <797> defines test requirements for low-, medium- and high-risk applications. In addition to these guidelines, scenarios unique to the facility should be tested (if not included in USP <797>). A typical test will involve various material processes (such as making solutions or transferring CSPs), containers (such as vials) and transfer methods (such as syringes).
  4. Incubate the test sample. Test samples are incubated for 14 days at a set temperature range — typically between 20 and 35 °C for defined periods for bacterial and fungal growth.
  5. Assess the results. If growth is found in the fill medium, the test will be a “fail,” meaning contamination occurred. A “pass” test shows no contamination and a successful media fill execution.
  6. Follow up. Personnel with fail results must be scheduled for additional training to bring their technique into compliance. Assigning these personnel to mentors to work with them until they are able to pass the test may also be considered. Pass tests should be met with vigilance, as an ongoing high standard must be kept to maintain the integrity of the facility and the work done there.

Media fill testing plays a critical role in your facility’s microbiological environmental monitoring and contamination control efforts. Technical Safety Services offers media fill kits for aseptic technique as part of our microbiological environmental monitoring services. We provide you with high-quality sterile medium to assure reliable testing. For more information, contact us today.


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