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antimicrobial susceptibility testing (AST)A
microbiological test to determine whether bacteria are susceptible or resistant
to an antibiotic. |
Clinical and Laboratory Standards Institute (CLSI)A
US-based organisation that promotes international laboratory standards and
guidelines for performing antibiotic susceptibility tests. |
clinical breakpointA discriminating concentration used in the interpretation of susceptibility tests to define isolates as susceptible or resistant. |
control strainsBacterial
isolates of known antibiotic sensitivity profile included in antimicrobial susceptibility testing (AST) to ensure that
the test is performed correctly. |
doubling dilutionsA
series of dilutions made so that the concentration of the antibiotic is reduced
by one half for each dilution step made. |
epidemiological cut-off (ECOFF)An agreed concentration of antibiotic that defines a wild type microorganism. The ECOFF reflects the ability to detect resistance mechanisms that may or may not be clinically significant in a susceptibility test. |
European Committee on Antimicrobial Susceptibility Testing (EUCAST)A
Europe-based organisation that promotes international laboratory standards and
guidelines for performing antibiotic susceptibility tests. |
genotypic methodsMethods based on the detection of genes. |
Gold StandardThe
best possible test for a given set of conditions. |
increased antibiotic exposure (I)A category
of isolates with a minimum inhibitory concentration (MIC) in the intermediate zone between definite susceptibility
and definite resistance to an antibiotic – as defined by EUCAST. |
inoculumThe microorganism suspension used to inoculate (or infect) something. |
International Standards Organisation (ISO)An
international body that has developed international quality standards for
microbiological laboratories. |
Kirby-Bauer methodThe
most commonly used disk diffusion method for antimicrobial susceptibility testing (AST). |
McFarland standardsReference standards that are used to adjust and standardise the turbidity of a bacterial
suspension. |
minimum bactericidal concentration (MBC)The lowest concentration of antimicrobial that kills a microorganism. |
minimum inhibitory concentration (MIC)The lowest concentration of an antimicrobial agent that inhibits the visible growth of a microorganism. |
One HealthA
concept that recognises the interdependency of human health and animal health, and
the ecosystems in which they evolve. |
pharmacodynamicsThe study of the biochemical and physiological effects of a drug on an organism. |
pharmacokineticsThe study of drug absorption, distribution, metabolism and excretion. |
phenotypic methodsMethods that rely on observable characteristics of the strain being tested. |
quality proceduresActivities
and processes that identify and minimise errors and ensure laboratory quality. Examples include quality control (QC), quality assurance (QA) and quality management system (QMS). |
resistance (R)A category
of isolates with a minimum inhibitory concentration (MIC) higher than the clinical breakpoint for a given
antibiotic – as defined by EUCAST |
standard operating procedures (SOPs)A document that details how routine laboratory processes and procedures should be performed. |
susceptible (S)A category
of isolates considered susceptible to antibiotic treatment following a standard
dosing regimen – as defined by EUCAST. |
turbidityA measure of how well light passes through a liquid. Light is scattered by particles in liquid, making them appear cloudy or turbid. Turbidity can be used to measure bacterial cell density. Samples with a high cell density will appear more turbid than those with a low cell density. |
zone of inhibitionThe clear region around a disk impregnated with antimicrobial in a disk diffusion test. It indicates that the isolate being tested is susceptible to the antimicrobial. |