Media fill testing is a crucial part of personnel qualification and environmental monitoring. During a media fill, technicians use microbiological growth media instead of a drug solution to assess whether the aseptic procedures performed are adequate to prevent contamination during sterile compounding.
USP 797 requires media fill testing before beginning to compound Category 1, 2, or 3 CSPs; and:
- Once every six months for Category 1 and 2
- Once every three months for Category 3
USP 797 also requires annual media fill testing for designated personnel. If a designated person also compounds, the individual must complete the aseptic manipulation competency at the same intervals required for compounding personnel.
Media Fill Design
Media fill simulates the most challenging compounding procedures and captures process areas that could potentially affect the sterility of CSPs, including:
- Factors associated with the length of the process that can pose contamination risk (e.g., operator fatigue, quality of equipment)
- Number of aseptic additions or transfers
- Number, type, and complexity of manipulations
- Number of personnel in the buffer room or SCA
Simulations should reflect the compounding activities conducted inside the Primary Engineering Control (PEC). If all starting components are sterile, simulate a sterile-to-sterile compounding activity. If some starting components are non-sterile, simulate a non-sterile to sterile compounding activity. Follow the media fill testing procedures outlined in USP 797, which can be accessed through the USP Compounding Compendium.
Once the compounding simulation is complete and the final containers are filled with the test media, perform a gloved fingertip and thumb sample on each hand and surface sample of the direct compounding area inside the PEC. Take the samples prior to disinfecting gloves and PEC. Handle and store samples to avoid contamination and incubate inverted to prevent condensate from dropping onto the agar during incubation and affecting the accuracy of the colony-forming unit (CFU) reading.
Incubate the final containers at 20°-25° C and 30°-35° C for a minimum of 7 days at each temperature to detect a broad spectrum of microorganisms. The order of the incubation temperatures must be described in the facility’s standard operating procedures (SOPs). Final containers must be incubated in an incubator. A media test failure is indicated by visible turbidity or other visual growth in the media in one or more container closure unit(s) on or before 14 days.
Incubate plates at 30°-35° C for no less than 48 hours and examine for growth. An actionable level for gloved fingertip and thumb sampling after media fill testing is >3 CFU, total from both hands.
Growth Media
The most common growth media is soybean casein digest medium (SCDM), which is also known as Trypticase Soy Broth (TSB). Growth media may be obtained from a commercial supplier or prepared in-house:
- If using a commercial supplier, a certificate of analysis (COA) must be obtained and state that the lot of growth media supports the growth of microorganisms. Suppliers are qualified by testing three batches of media using quality control tests: growth promotion, pH, sterility, and visible inspection.
- If preparing growth media in house, growth promotion of the media must be demonstrated for each batch and documented as described in Sterility Tests USP 71.
Media Fill Controls
A media fill is an experiment that should include controls. These controls should be independent of the growth promotion testing.
A positive control is a sealed product container of media inoculated with a small number of microorganisms. If growth occurs, the positive control demonstrates that the media can promote the growth of the organism(s). The positive control should be inoculated in an area separate from the compounding area.
A negative control is prepared by transferring media into a separate sterile container and incubating the control with the media fill test containers. The negative control should not show microorganism growth proving the media was sterile at the start.
ARL Services
ARL provides testing services to assist compounders with personnel qualification and environmental monitoring.
- Growth Promotion – this test demonstrates that the media used in environmental monitoring programs, media fills, or personnel qualification are capable of supporting microorganism growth. ARL tests according to client instructions and provides a certificate of analysis for specific microorganisms.
- Incubation / Observation – this test incubates and observes the media and plate samples according to client instructions and provides a certificate of analysis with CFU count.
- Microbial Identification – this test identifies microorganisms isolated during incubation and observation and tests the genus/species level using DNA sequencing.
Contact ARL for more information on testing at 800-393-1595 or info@arlok.com.
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