Method Suitability Testing — Bacteriostasis & Fungistasis
Method suitability testing — also called B/F testing — is the prerequisite that makes every sterility test you run defensible. Boulder BioLabs executes method suitability studies using protocols aligned with ISO 11737-2 and USP <71>, operating under the Boulder BioMed ISO 13485 quality management system.
What Is Method Suitability Testing?
A sterility test asks: if there were a microbe on this device, would the test recover it? If the device material is bacteriostatic or fungistatic, the answer might be "no" even when the device is contaminated. Method suitability validates that the test method recovers indicator organisms in the presence of the device material.
We inoculate the device (or extract) with low levels of S. aureus, P. aeruginosa, B. subtilis, C. albicans, A. brasiliensis, and C. sporogenes per the USP <71> indicator panel and confirm recovery of each.
Why It Matters
Skipping method suitability is one of the most common 483 finding categories in medical device sterility programs. An inspector pulling a sterility record will ask for the method suitability that validates it. The cost of doing it right at the start is small. The cost of doing it later, under pressure, is not.
Our Process
- Method selection — direct inoculation vs. membrane filtration.
- Inoculation at <100 CFU of each USP <71> indicator.
- Incubation and recovery per USP <71> / ISO 11737-2.
- Modification if recovery fails — re-validated until recovery is demonstrated.
- Reporting — referenced by every subsequent sterility test on that device family.