Fingertip Testing
See Compounding Sterile Preparations starting at page 447 for more info about this. This is a procedure that is recommended to be performed on occasion but not at every brew. In a compounding pharmacy, a technician must pass this test 3 times before being allowed to compound sterile medications for human consumption.1
In short, you start with 6 agar plates. At the start of your process, as soon as you glove and sanitize your gloves, you take a print of each of your fingers and thumb onto agar plates, one for the digits on each hand. Then once you finish your preparation you take another sample from each hand. You should not sterilize your gloves immediately prior to the final sample as this could create a false negative. Label each plate as which hand and if the sample was collected before or after making your preparation.
Take one more agar plate and leave it exposed to the air in your home for 5-10 minutes. Your final plate should remain sealed. These are your positive and negative controls.
Tape shut around the edges. Store/incubate inverted. If you can, incubate at 30–35°C/86-95°F for 48–72 hours.1 If you do not have access to an incubator, leave at room temperature in a warm spot in your house. Instead of waiting 72 hours you may need to wait a week. Use your control sample that you left exposed to the air to help you determine when there is visible growth.
According to the standards set forth in USP 797, if you show any pinpoints of growth on the two collections you took before compounding, or if you show more than 3 pinpoints of growth on the two plates collected after you finished compounding, then your sterile technique is lacking.
Failed test?
If you were working in a compounding pharmacy, and you failed fingertip testing you would not be cleared to compound for human use. Therefore, your vials you just made would not be cleared. You will need to rectify how you want to play this for yourself. If it was a minor failure maybe it’s easy to justify using the vials. If it’s a major failure you might be more cautious and decide to withdraw the preparations, re-filter, and dispense into new, clean vials.