PDA Glossary

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

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

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

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)

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

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)

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

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

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

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)

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)

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)

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)

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)

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)