Bioburden testing

Clontz, L., Microbial Limit and Bioburden Tests, Interpharm Press, Buffalo Grove, IL, 1998. 

Bioburden testing is performed on components prior to steam sterilization as verification that the sterilization parameters are sufficient for sterilization of components. The method for determining the bioburden level of components is included in the manufacturing site standard test method. For product component bioburden summary, refer to (provide reference attachment number). 

It should be noted that bioburden testing (or viable counts) is an integral part of environmental testing, and it is very useful information to complement the effort to validate heat sterilization. The FDA position on terminal sterilization [27] supports the correctness of this statement. 

Bioburden testing is required for biologies used in pivotal preclinical studies to support clinical development and registration. Endotoxin levels are the primary concern in this regard. There are several major regulatory documents listed below (taken from Associates of Cape Cod Inc. Web site http //www. acciusa.com/) that describe how drugs, devices, dialysate, water, and other substances are to be tested for endotoxin. 

C. Interpretation of Results—Particulate Matter Testing XVIII. BIOBURDEN TESTING OF PARENTERAL PRODUCT... 

In this section only the bioburden determination of a parenteral product solution for aerobic isolates is discussed and details regarding bioburden testing of facility or equipment surfaces are not included. For parenteral products, bioburden is usually estimated on the unfiltered bulk product solution (UBPS). In this way the test will indicate the total microbial load culminating in the batch solution as a result of the various contributing factors such as all batch ingredients, manual manipulations, and environmental fallout. Testing of filtered bulk parenteral solution either before or after filling into the final container may be done for comparison to the previously tested unfiltered bulk solution or to comply with the directives from European inspectors. All isolates should be identified to the species level whenever possible. The... 

Microbial limit tests, as described in USP 24-NF 19 (<61>) provide the information necessary to conduct bioburden counts by quantitative estimations of viable aerobic microorganisms in pharmaceutical articles, raw materials, and finished dosage forms. Consult the EP or JP for any differences in these methods from those of the USP. Note that USP (<61>) is currently under revision and that the next version will be fully harmonized between the USP, EP, and JP. The microbial limit test comprises the total aerobic bacterial (microbial) count (TAG), the total combined yeasts and molds count (TYMC), and tests for indicator organisms. Bioburden tests are also referred to as total viable counts. This test estimates the total number of viable (culturable) aerobic microorganisms in various items including parenteral UBPS. The total viable count is obtained by adding the counts from the TAC and the TYMC. 

Drying is a unit operation where multiple batches of coprecipitate can be combined to gain production efficiencies. In such cases, wet MBP can be stored in a refrigerator for an extended period, but only if the amorphousness of wet MBP is ensured. It has been observed that, if not properly stored, mold and fungi can grow in the wet cake. Bioburden tests should be performed prior to drying in cases where the wet cake needs to be stored for extended period of time before drying. 

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