USP<797>

To conduct a gloved fingertip test (GFT) the trainee lightly presses the fingers and thumb of each hand onto an agar plate containing general growth medium (e.g. TSA w/ lecithin and polysorbate). Successful completion of the GFT sampling is defined as ≤3 cfu and 0 cfu as a total from both hands after media-fill testing and after garbing, respectively. Personnel must successfully complete an initial garbing competency evaluation no fewer than 3 separate times.

Agar plates with general microbial growth medium (e.g., TSA) for gloved fingertip testing must contain neutralizing agents (e.g. lecithin and polysorbate) and are incubated at 30 to 35°C for no less than 48 hours followed by incubation at 20 to 25°C for no less than additional 5 days. All microbial colonies are counted and reported.

The media fill test assesses the sterile technique of the trainee and related practices. The test can be performed by substituting liquids in the compounding process with microbial growth medium (e.g., Tryptic Soy Broth, TSB) or by using media fill test kits that can be purchased commercially. In either case, the media fill test must simulate the most difficult and challenging compounding procedures and processing conditions encountered by the trainee.

Media fill vials are incubated at 20 to 25°C for 7 days followed by incubation at 30 to 35°C for additional 7 days. Any observed microbial growth before or at completion of the incubation time triggers failure of the test.

Air sampling for the certification of cleanrooms includes nonviable particle counts on site (ISO14644) as well as air monitoring for viable particles, i.e. microbial contamination.  For category 1 and 2 compounding, viable particles must be collected at least every six months via volumetric sampling as part of the re-certification of the facility. For category 3 compounding viable air testing is required at least every 3 months. A minimum of one air sample is needed for each classified area with sample volume of 1000 liters or more on general microbial growth medium (e.g., Tryptic Soy Agar, TSA). 

If one air sample per location is collected, media plates are incubated at 30 to 35°C for no less than 48 hours followed by incubation at 20 to 25°C for no less than additional 5 days. Alternatively, two samples per location with at least 1000 liters can be collected for concurrent incubation at each of the two temperatures. Both plates can contain a general microbial growth medium (TSA) or the second plate can hold a fungal growth medium (e.g., Sabouraud Dextrose Agar, SDA). If two samples per location are submitted, the fungal growth medium is incubated at the lower temperature for no less than 5 days.

The number of microbial colonies including bacteria, yeasts and molds must be below action levels for each ISO classification. Identification of microbial colonies must be attempted to at least genus level whenever the numbers exceed threshold levels and excursions must be investigated.

In the recent (2023) revision of General Chapter USP<797> surface testing takes a much more significant role. Category 1 and 2 sterile compounding requires surface testing at least monthly and category 3 is sampled weekly at all ISO classified areas as well the direct compounding area after each batch and before cleaning. In addition, surface testing must be performed after media fill testing as part of the personnel training. The main media type is contact plates or media paddles. Swabs are only allowed for uneven surfaces.

If one surface sample per location is collected, media plates are incubated at 30 to 35°C for no less than 48 hours followed by incubation at 20 to 25°C for no less than additional 5 days. Alternatively, two samples per location can be collected for concurrent incubation at each of the two temperatures. Both plates can contain a general microbial growth medium with neutralizing additives (TSA w/ lecithin and polysorbate) or the second plate can hold a fungal growth medium (e.g., Sabouraud Dextrose Agar, SDA w/ lecithin and polysorbate). If two samples per location are submitted, the fungal growth medium is incubated at the lower temperature for no less than 5 days.

The number of microbial colonies including bacteria, yeasts and molds must be below action levels for each ISO classification. Identification of microbial colonies must be attempted to at least genus level whenever the numbers exceed threshold levels and excursions must be investigated.