
PDA Technical Glossary
PDA Technical Reports are highly valued membership benefits because they offer expert guidance and opinions on important scientific and regulatory topics and are used as essential references by industry and regulatory authorities around the world. These reports include terms which explain the material and enhance the reader’s understanding.
The database presented here includes the glossary terms from all current technical reports. The database is searchable by keyword, topic, or by technical report. Each definition provided includes a link to the source technical report within the PDA Technical Report Portal.
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- TR 47: Virus Spikes/Virus Clearance (1)
- TR 51: Biological Indicators (1)
- TR 55: TBA/TCA Detection Mitigation (1)
- TR 61: Steam in Place (1)
- TR 62: Manual Aseptic Processes (1)
- TR 69: Bioburden/Biofilm Management (1)
- TR 70: Cleaning/Disinfection Programs (1)
- TR 13: Environmental Monitoring (1)
- TR 22: Aseptic Process Simulation (1)
- TR 26: Sterilizing Filtration of Liquids (1)
- TR 45: Depth Filtration (1)
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Bioburden
The total number of microorganisms per unit of material prior to sterilization. (TR13) Total number of viable microorganisms on or in a health care product prior to sterilization. (TR22)(TR61)(TR62) A population of viable microorganisms in a fluid prior to sterilizing filtration. (TR26) A measure of the contaminating organisms found in or on a given amount of material before it undergoes a sterilization process. (TR45) (TR70) The number of detectable microorganisms (bacteria and fungi) with which an object is contaminated. It is measured in CFU (colony forming units). (TR47) The number of viable, contaminating microorganisms present on a product immediately prior to decontamination. (TR51) Viable microbial contaminants associated with personnel manufacturing environments (air and surfaces), equipment, product packaging, raw materials (including water), in-process materials, and finished products. (TR 67) (TR 69)
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Frank (Canonical) Pathogens
Microorganisms responsible for infection in healthy individuals (i.e., individuals with normal operative and functional host defense mechanisms) that may be acquired from exposure to other infected people or animals, environmental reservoirs (exogenous) or the individual’s normal (endogenous) microbial flora. (TR67)
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Microbial Enumeration
Compendial test for microbial counts using the plate-count, membrane-filtration or most probable number methods described in USP <61> Microbiological Examination of Nonsterile Products: Microbial Enumerations Tests. (TR67)
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Microbiological Examination Tests
The compendial tests for microbial enumeration and absence of specified microorganisms as found in USP <61> Microbiological Examination of Nonsterile Products: Microbial Enumerations Tests and USP <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms. (TR67)
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Microorganism of Concern
A bacterium, yeast, or mold that, due to it prominence in product recalls, infection outbreaks, nosocomial infections, and the clinical literature, results in a multifactor risk assessment to determine whether the microorganism is objectionable if it is present in a specific nonsterile product. (TR67)
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Opportunistic Pathogens
Microorganisms responsible for infection in injured, invasively treated or immune-suppressed individuals that typically do not cause infection in healthy individuals, unlike frank pathogens. (TR67)
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Specified Microorganisms
Microorganisms with limit tests for absence in 1 or 10 g of a drug product, as described in USP <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms and USP <1111> Microbiological Quality of Nonsterile Pharmaceutical Products: Acceptance Criteria for Pharmaceutical Preparations and Substances for Pharmaceutical Use. (TR67)
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Water Activity (Aw)
Water Activity, Aw is the ratio of the vapor pressure of water in a product (P) to the vapor pressure of water in a product (P) to the vapor pressure of pure water (Po) at the same temperature. It is numerically equal to 1/100 of the RH generated by the product in a closed system. It is a measure of the free or available moisture in the material. Note: Water activity ≠ water content. RH can be calculated from direct measurements partial vapor pressure or dew point, or from indirect measurements by sensors whose physical or electric characteristics are altered by the RH to which they are exposed. Microorganisms need available water within a pharmaceutical product, as well as nutrients and minerals, to proliferate. Water activity, and not water content, is a better measure of the free water, in contrast to bound water that microbial cells require for metabolic activity and osmotic regulation. Effects of reduced Aw on microbial growth include a longer lag phase, slower growth rate, lower numbers of organisms in the stationary phase, and reduced microbial toxin production; below a specified Aw for an organism, microbial growth will not occur. (TR55) (TR67)