| Revision as of 23:25, 28 September 2018 editWerdna (talk | contribs)Extended confirmed users6,655 edits Correct definition of D value - it is the value required to kill 90% of organisms, not 100%.Tag: Visual edit← Previous edit | Latest revision as of 07:56, 3 December 2023 edit undoCitation bot (talk | contribs)Bots5,414,854 edits Add: doi-access, authors 1-1. Removed parameters. Some additions/deletions were parameter name changes. | Use this bot. Report bugs. | Suggested by Headbomb | #UCB_toolbar | ||
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| {{Short description|Time (or dose of an antimicrobial) required to kill 90% microbes}} | |||
| ⚫ | In ], '''D-value''' |
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| {{more cn|date=October 2022}} | |||
| ⚫ | In ], in the context of a ] procedure, the '''D-value''' or '''decimal reduction time''' (or '''decimal reduction dose''') is the time (or dose of an ]) required, at a given condition (e.g. ]) or set of conditions, to achieve a one-], that is, to kill 90% of relevant ].<ref>{{Cite web|url=https://www.fda.gov/iceci/inspections/inspectionguides/ucm070835.htm|title=Inspection Guides - Sterilizing Symbols (D, Z, F)|last=U.S. Food and Drug Administration|website=www.fda.gov|access-date=2018-09-28}}</ref> A D-value is denoted with the capital letter "D". Thus, after an exposure time of 1 D, only 10% of the organisms originally present in a ] would remain. The term originated in assessments of microbes' thermal resistance and in ] analysis; however, it now has analogous uses in other microbial resistance and death rate applications, such as for ] and ] 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 ]-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° ] for 20 minutes, the D-value would be written as D<sub>150C</sub> = 20 minutes. If generally describing D-value for any temperature, a common abbreviation is D<sub>T</sub> (where T is temperature) until a value for T is relevant to express, specifically. Another more general abbreviated expression of D-value is D<sub>10</sub> (as to denote 10% reduction). | |||
| ==Details== | |||
| ⚫ | D- |
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| Use of D-values is based on the assumption that the procedure in question causes the number of living microorganisms to ]. From this perspective, D-values can be understood as roughly analogous to ] of radioactive substances, however a half life involves a reduction of 50% rather than 90%. The half life is actually roughly 30% ({{math|log<sub>10</sub>2 ≈ 30.103%}}) of the D-value, so if D = 10 minutes, the number of living microorganisms will be halved in about 3 minutes. | |||
| Generally, each lot of a ]-resistant organism will have its own specific D-value. Determining a D-value requires an experiment, but only gives the D-value under the specific conditions of that experiment. D-values are unique to the conditions of the environment that the bacteria currently exists in.<ref>{{Cite journal|last1=Channaiah|first1=Lakshmikantha H.|last2=Michael|first2=Minto|last3=Acuff|first3=Jennifer C.|last4=Lopez|first4=Keyla|last5=Phebus|first5=Randall K.|last6=Thippareddi|first6=Harshavardhan|last7=Milliken|first7=George|date=2019-04-02|title=Validation of a nut muffin baking process and thermal resistance characterization of a 7-serovar Salmonella inoculum in batter when introduced via flour or walnuts|journal=International Journal of Food Microbiology|volume=294|pages=27–30|doi=10.1016/j.ijfoodmicro.2019.01.013|pmid=30739832|issn=0168-1605|doi-access=free}}</ref> | |||
| In the context of thermal analysis it is typical practice to subscript the "D" with an indication of temperature. For example, given a hypothetical organism which is reduced by 90% after exposure to temperatures of 150° ] for 20 minutes, the D-value would be written as D<sub>150C</sub> = 20 minutes. In the US, the temperature is usually indicated in ]; a notation like D<sub>230</sub> should be understood to mean D<sub>230F</sub> (D<sub>110C</sub>). When describing D-value generally for any temperature, like in the heading of a table, a common abbreviation is D<sub>''T''</sub> (where ''T'' stands for the temperature), where specific values for ''T'' may be given elsewhere. A numeric subscript may also be used to indicate some other level of reduction than 90%; for example, D<sub>10</sub> denotes the time required for a 10% reduction. | |||
| ⚫ | D-values are sometimes used to express a ]'s efficiency in reducing the number of microbes present in a given environment.<ref>{{cite journal |title=Determination of decimal reduction time (D value) of chemical agents used in hospitals for disinfection purposes |journal=BMC Infectious Diseases |doi=10.1186/1471-2334-3-24 |pmid=14563217 |author=Priscila Gava Mazzola, Thereza Christina Vessoni Penna, Alzira M da S Martins |volume=3 |pages=24 |date=17 October 2003|pmc=270032 |doi-access=free }}</ref> | ||
| ==See also== | ==See also== | ||
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Latest revision as of 07:56, 3 December 2023
Time (or dose of an antimicrobial) required to kill 90% microbes | This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "D-value" microbiology – news · newspapers · books · scholar · JSTOR (October 2022) (Learn how and when to remove this message) |
In microbiology, in the context of a sterilization procedure, the D-value or decimal reduction time (or decimal reduction dose) is the time (or dose of an antimicrobial drug) required, at a given condition (e.g. temperature) or set of conditions, to achieve a one-log reduction, that is, to kill 90% of relevant microorganisms. A D-value is denoted with the capital letter "D". Thus, after an exposure time of 1 D, only 10% of the organisms originally present in a microbial colony would remain. The term originated in assessments of microbes' thermal resistance and in thermal death time analysis; however, it now has analogous uses in other microbial resistance and death rate applications, such as for ethylene oxide and radiation processing.
Details
Use of D-values is based on the assumption that the procedure in question causes the number of living microorganisms to decay exponentially. From this perspective, D-values can be understood as roughly analogous to half lives of radioactive substances, however a half life involves a reduction of 50% rather than 90%. The half life is actually roughly 30% (log102 ≈ 30.103%) of the D-value, so if D = 10 minutes, the number of living microorganisms will be halved in about 3 minutes.
Generally, each lot of a sterilization-resistant organism will have its own specific D-value. Determining a D-value requires an experiment, but only gives the D-value under the specific conditions of that experiment. D-values are unique to the conditions of the environment that the bacteria currently exists in.
In the context of thermal analysis it is typical practice to subscript the "D" with an indication of temperature. 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. In the US, the temperature is usually indicated in degrees Fahrenheit; a notation like D230 should be understood to mean D230F (D110C). When describing D-value generally for any temperature, like in the heading of a table, a common abbreviation is DT (where T stands for the temperature), where specific values for T may be given elsewhere. A numeric subscript may also be used to indicate some other level of reduction than 90%; for example, D10 denotes the time required for a 10% reduction.
D-values are sometimes used to express a disinfectant's efficiency in reducing 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.
- Channaiah, Lakshmikantha H.; Michael, Minto; Acuff, Jennifer C.; Lopez, Keyla; Phebus, Randall K.; Thippareddi, Harshavardhan; Milliken, George (2019-04-02). "Validation of a nut muffin baking process and thermal resistance characterization of a 7-serovar Salmonella inoculum in batter when introduced via flour or walnuts". International Journal of Food Microbiology. 294: 27–30. doi:10.1016/j.ijfoodmicro.2019.01.013. ISSN 0168-1605. PMID 30739832.
- 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. PMC 270032. PMID 14563217.
{{cite journal}}: CS1 maint: multiple names: authors list (link)