Skip To The Main Content

PDA Glossary

PDA Glossary of Pharmaceutical and Biotechnology Terminology

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.

Browse Terms by Title


Browse Terms by TR #

  • Acholeplasma laidlawii

    A. laidlawii is a mycoplasma in class Mollicutes and order Acholeplasmatales. (TR75)

  • Challenge Concentration

    The concentration in Colony Forming Units/mL of the test microorganism in the challenge fluid. (TR75)

  • Challenge Fluid

    The carrier fluid in which the test microorganism is suspended and delivered to the test filter. (TR75)

  • Challenge Level

    The concentration of the test microorganism applied to the test filter (per centimeter squared) or the total number of cells applied to the test filter at the completion of the challenge. (TR75)

  • Challenge Volume

    The volume of challenge fluid applied to the test filter. (TR75)

  • Colony Forming Unit (CFU)

    One or more microorganisms that produce a visible, discrete growth entity on a semi-solid, agar-based microbiological medium. (TR22) (TR62)

    Visible outcome of growth of microorganisms arising from a single or multiple cells. (TR28)

    A single microorganism or an aggregate of many that forms a single discrete colony on solid agar media after suitable incubation. Colony forming units are used for bacterial titer (total bacteria load in a sample) determination on solid media. (TR50) (TR75)

  • Culture Medium

    The nutritional medium which supports the growth of the given microorganism. (TR75)

  • Filter Rating

    A numerical rating of filter performance based on the ability of the filter to retain an appropriate model microorganism under given test conditions. (TR75)

  • Kilopascal (kPa)

    The International System of Units derived unit of pressure. (TR75)

  • Log Reduction Value (LRV)

    The logarithm to the base 10 of the ratio of organisms in the feed to organisms in the filtrate. (i.e., Log10(109/2) = 9.7). [Synonym: Log Titer Reduction] (TR45)

    Titer Reduction (TR) expressed as a base 10 logarithm. (TR75)

  • Mycoplasma Reduction Filter

    A sterilizing grade filter that also provides a log reduction value (or a titer reduction value) for a specified test mycoplasma according to the PDA Mycoplasma Consensus Method. (TR75)

  • Positive Control Filter Membrane (Penetration Control)

    A control filter membrane with a larger pore size rating than the test filter and used to demonstrate the penetrative ability of the test microorganism. Penetration of this filter by at least one CFU is required to validate a test. (TR75)

  • Psid

    Pound-force per square-inch differential is the difference in pressure; for example, the pressure differential between the upstream (influent) and downstream (effluent) sides of a filter. (TR75)

  • Sterilizing Grade Filter

    A filter intended for terminal processing of sterile liquids that has been tested under worst-case actual processing conditions for the ability to retain a minimum challenge of 107 cells of Brevundimonas diminuta per cm2 of filter area. (TR41)

    A filter that reproducibly removes all test microorganisms from the process stream, producing a sterile effluent. (TR75)

    A filter that reproducibly removes test microorganisms from the process stream, producing a sterile filtrate. (TR26)

  • Titer Reduction (TR)

    A measure of the degree to which a particular filter removes a microorganism under specified test conditions. Calculated as the ratio of the total number of microorganisms used to challenge the filter divided by the total number of microorganisms that passed through the filter. (TR75)