This is an old revision of this page, as edited by Werdna (talk | contribs) at 23:25, 28 September 2018 (Correct definition of D value - it is the value required to kill 90% of organisms, not 100%.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 23:25, 28 September 2018 by Werdna (talk | contribs) (Correct definition of D value - it is the value required to kill 90% of organisms, not 100%.)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)In microbiology, D-value refers to decimal reduction time (or decimal reduction dose) and is the time (or dose) required at a given condition (e.g. temperature), or set of conditions, to kill 90% (or 1 log) of the exposed microorganisms. The term originated from assessing microbial thermal resistance and thermal death time analysis; however, it has analogous uses in other microbial resistance and death rate applications, such as (but not limited to) those of ethylene oxide and radiation processing.
Thus after a colony is reduced by 1 D, only 10% of the original organisms remain, i.e., the population number has been reduced by one decimal place in the counting scheme. Generally, each lot of a sterilization-resistant organism is given a unique D-value. When referring to D-values, for the purpose of thermal analysis, it is proper to give the temperature as a subscript of the "D". For example, given a hypothetical organism which is reduced by 90% after exposure to temperatures of 150° C for 20 minutes, the D-value would be written as D150C = 20 minutes. If generally describing D-value for any temperature, a common abbreviation is DT (where T is temperature) until a value for T is relevant to express, specifically. Another more general abbreviated expression of D-value is D10 (as to denote 10% reduction).
D-value determination is sometimes carried out to measure a disinfectant's efficiency to reduce the number of microbes present in a given environment.
See also
References
- U.S. Food and Drug Administration. "Inspection Guides - Sterilizing Symbols (D, Z, F)". www.fda.gov. Retrieved 2018-09-28.
{{cite web}}: Cite has empty unknown parameter:|dead-url=(help) - Priscila Gava Mazzola, Thereza Christina Vessoni Penna, Alzira M da S Martins (17 October 2003). "Determination of decimal reduction time (D value) of chemical agents used in hospitals for disinfection purposes". BMC Infectious Diseases. 3: 24. doi:10.1186/1471-2334-3-24.
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