• Include these codes as defined in http://terminology.hl7.org/CodeSystem/v3-ObservationInterpretation version 📍2.1.0

  Code	Display	Definition
  I	Intermediate	Bacterial strain inhibited in vitro by a concentration of an antimicrobial agent that is associated with uncertain therapeutic effect. Reference: CLSI (http://www.clsi.org/Content/NavigationMenu/Resources/HarmonizedTerminologyDatabase/Harmonized\_Terminolo.htm) Projects: ISO 20776-1, ISO 20776-2 \[Note 1: Bacterial strains are categorized as intermediate by applying the appropriate breakpoints in a defined phenotypic test system.\] \[Note 2: This class of susceptibility implies that an infection due to the isolate can be appropriately treated in body sites where the drugs are physiologically concentrated or when a high dosage of drug can be used.\] \[Note 3: This class also indicates a "buffer zone," to prevent small, uncontrolled, technical factors from causing major discrepancies in interpretations.\] \[Note 4: These breakpoints can be altered due to changes in circumstances (e.g., changes in commonly used drug dosages, emergence of new resistance mechanisms).\]
  IE	Insufficient evidence	There is insufficient evidence that the species in question is a good target for therapy with the drug. A categorical interpretation is not possible. \[Note: A MIC with "IE" and/or a comment may be reported (without an accompanying S, I or R-categorization).\]
  MS	moderately susceptible	The patient is considered as carrier based on the testing results. A carrier is an individual who carries an altered form of a gene which can lead to having a child or offspring in future generations with a genetic disorder. ***Deprecation Comment:*** This antimicrobial susceptibility test interpretation concept is recommended by OO to be deprecated as it is no longer recommended for use in susceptibility testing by CLSI (reference CLSI document M100-S22; Vol. 32 No.3; CLSI Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Second Informational Supplement. Jan 2012).
  NCL	No CLSI defined breakpoint	Use when not enough clinical trial data published by the Clinical and Laboratory Standards Institutes (CLSI) is available to establish the breakpoints for susceptible / intermediate and resistant.
  NS	Non-susceptible	A category used for isolates for which only a susceptible interpretive criterion has been designated because of the absence or rare occurrence of resistant strains. Isolates that have MICs above or zone diameters below the value indicated for the susceptible breakpoint should be reported as non-susceptible. NOTE 1: An isolate that is interpreted as non-susceptible does not necessarily mean that the isolate has a resistance mechanism. It is possible that isolates with MICs above the susceptible breakpoint that lack resistance mechanisms may be encountered within the wild-type distribution subsequent to the time the susceptible-only breakpoint is set. NOTE 2: For strains yielding results in the "nonsusceptible" category, organism identification and antimicrobial susceptibility test results should be confirmed. Synonym: decreased susceptibility.
  R	Resistant	Bacterial strain inhibited in vitro by a concentration of an antimicrobial agent that is associated with a high likelihood of therapeutic failure. Reference: CLSI (http://www.clsi.org/Content/NavigationMenu/Resources/HarmonizedTerminologyDatabase/Harmonized\_Terminolo.htm) Projects: ISO 20776-1, ISO 20776-2 \[Note 1: Bacterial strains are categorized as resistant by applying the appropriate breakpoints in a defined phenotypic test system.\] \[Note 2: This breakpoint can be altered due to changes in circumstances (e.g., changes in commonly used drug dosages, emergence of new resistance mechanisms).\]
  S	Susceptible	Bacterial strain inhibited by in vitro concentration of an antimicrobial agent that is associated with a high likelihood of therapeutic success. Reference: CLSI (http://www.clsi.org/Content/NavigationMenu/Resources/HarmonizedTerminologyDatabase/Harmonized\_Terminolo.htm) Synonym (earlier term): Sensitive Projects: ISO 20776-1, ISO 20776-2 \[Note 1: Bacterial strains are categorized as susceptible by applying the appropriate breakpoints in a defined phenotypic system.\] \[Note 2: This breakpoint can be altered due to changes in circumstances (e.g., changes in commonly used drug dosages, emergence of new resistance mechanisms).\]
  SDD	Susceptible-dose dependent	A category that includes isolates with antimicrobial agent minimum inhibitory concentrations (MICs) that approach usually attainable blood and tissue levels and for which response rates may be lower than for susceptible isolates. Reference: CLSI document M44-A2 2009 "Method for antifungal disk diffusion susceptibility testing of yeasts; approved guideline - second edition" - page 2.
  SYN-R	Synergy - resistant	A category for isolates where the bacteria (e.g. enterococci) are not susceptible in vitro to a combination therapy (e.g., high-level aminoglycoside and cell wall active agent). This is predictive that this combination therapy will not be effective. *Usage Note:* Since the use of penicillin or ampicillin alone often results in treatment failure of serious enterococcal or other bacterial infections, combination therapy is usually indicated to enhance bactericidal activity. The synergy between a cell wall active agent (such as penicillin, ampicillin, or vancomycin) and an aminoglycoside (such as gentamicin, kanamycin or streptomycin) is best predicted by screening for high-level bacterial resistance to the aminoglycoside. *Open Issue:* The print name of the code is very general and the description is very specific to a pair of classes of agents, which may lead to confusion of these concepts in the future should other synergies be found.
  SYN-S	Synergy - susceptible	A category for isolates where the bacteria (e.g. enterococci) are susceptible in vitro to a combination therapy (e.g., high-level aminoglycoside and cell wall active agent). This is predictive that this combination therapy will be effective. *Usage Note:* Since the use of penicillin or ampicillin alone often results in treatment failure of serious enterococcal or other bacterial infections, combination therapy is usually indicated to enhance bactericidal activity. The synergy between a cell wall active agent (such as penicillin, ampicillin, or vancomycin) and an aminoglycoside (such as gentamicin, kanamycin or streptomycin) is best predicted by screening for high-level bacterial resistance to the aminoglycoside. *Open Issue:* The print name of the code is very general and the description is very specific to a pair of classes of agents, which may lead to confusion of these concepts in the future should other synergies be found.
  VS	very susceptible	The patient is considered as carrier based on the testing results. A carrier is an individual who carries an altered form of a gene which can lead to having a child or offspring in future generations with a genetic disorder. ***Deprecation Comment:*** This antimicrobial susceptibility test interpretation concept is recommended by OO to be deprecated as it is no longer recommended for use in susceptibility testing by CLSI (reference CLSI document M100-S22; Vol. 32 No.3; CLSI Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Second Informational Supplement. Jan 2012).

This value set expansion contains 11 concepts.