The microbial enumeration test, also called the bioburden test or the microbial load test, is performed to monitor the microbial content in raw materials, in-process samples, and finished product in the pharmaceutical, biological, cosmetics, nutritional products, and medical device industry. The FDA expects companies to monitor the bioburden load in products used for humans and animals. The bioburden test can be performed by several methods based on the nature of the material tested.
The following is a list of the extraction methods offered. The extraction method is the procedure for removing the microorganisms from the product being tested.
- Immersion
- Flush / Rinse
- Surface Sampling
- Dilution
The following is a list of the enumeration methods offered. The enumeration method is the procedure used to determine the number of viable microorganisms that are extracted from the product being tested.
- Membrane Filtration
- Direct Plating
- Most Probable Number (MPN)
The microbial load test should be validated to ensure that the method is effective, accurate, and reproducible in determining the material’s microbial load in a test article. The most suitable methodology should be determined as part of method development. Validation will be performed with the method that shows the best recovery of organisms with no inhibition. Validation is performed per USP/EP for Pharmaceutical or Biotechnology products, and AAMI for medical devices. Cosmetics are tested per FDA BAM manual.
MQA can also develop custom bioburden procedures for samples that are difficult to test.
| Assay Description | Service Code | Sample Requirements |
|---|---|---|
| Aerobic Bioburden by Membrane Filtration – TSA medium only | ML01 | > 10 mL or grams |
| Anaerobic Bioburden by Membrane Filtration | ML02 | > 10 mL or grams |
| Yeast and Mold Bioburden – Membrane Filtration | ML03 | > 10 mL or grams |
| Total Aerobic Bioburden by Membrane Filtration (TSA & SDA media) (bacteria & fungi) | ML04 | > 20 mL or grams |
| USP <61> Microbial Enumeration Test Bacterial & Fungal count | ML05 | > 20 mL or grams |
| Aerobic Bioburden by Pour Plate method (TSA only) | ML06 | > 10 mL or grams |
| Anaerobic Bioburden by Pour Plate method (TSA only) | ML07 | > 10 mL or grams |
| Yeasts and Molds Bioburden by Pour Plate method (SDA medium) | ML08 | > 10 mL or grams |
| Total Aerobic Bioburden by Pour Plate method (bacteria & fungi) (TSA & SDA media) | ML09 | > 10 mL or grams |
| Microbial load inhibition test per USP | ML10 | > 30 mL or grams |
| Microbial load inhibition test per USP – membrane filtration plate count – TSA and SAB media + 6 USP org | ML11 | >30 mL or grams |
| Microbial load inhibition test – pour plate count – TSA and SAB + 6 org | ML12 | >30 mL or grams |
| Custom bioburden studies | ML13 | Project specific |
| MPN test | ML14 | > 10 mL or grams |
| Cosmetics aerobic plate count (APC) | ML15 | > 10 mL or grams |
| Cosmetics anaerobic plate count | ML16 | > 10 mL or grams |
| Cosmetics fungal count | ML17 | > 10 mL or grams |
| Cosmetic preservative efficacy test | ML18 | > 10 mL or grams |
| Cosmetics APC on non-used and used product | ML19 | > 10 mL or grams |
Please note: The microbial load test is performed on an undiluted sample. Additional dilutions will be an additional charge. Microbial load liquid samples must be shipped cold. Liquid samples will be tested within 24 hours of receipt at the lab. Samples should be collected in sterile containers.
