Antimicrobial wild type MIC distributions of microorganisms

Database Sept 4, 2008: 17 832 MIC distributions

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Should you have problems when accessing the website - please send a mail to
 gunnar.kahlmeter@ltkronoberg.se or larsgunnar.jacobsson@st.se
 

MIC distributions released by EUCAST: 

• Amikacin, Gentamicin, Netilmicin, Tobramycin

• Ciprofloxacin, Levofloxacin, Moxifloxacin, Norfloxacin, Ofloxacin

• Linezolid

• Teicoplanin, Vancomycin

• Ertapenem, Imipenem, Meropenem

• Cefepime, Cefotaxime, Cefoxitin, Ceftazidime, Ceftriaxone, Cefuroxime

• Aztreonam

• Daptomycin

• Tigecycline

• Macrolides and related antimicrobials

• Miscellaneous antimicrobials

• Tetracyclines

• Penicillins
   

• Fluconazole

• Voriconazole

The following antimicrobials are now being adressed:

• Oral cephalosporins

To contribute MIC-distribution data for bacteria or fungi, please download one of the following Excelfiles, complete it following the instructions in the Excel-sheet and mail it to gunnar.kahlmeter@ltkronoberg.se

To cite data from the EUCAST program, use:

"Data from the European Committee on Antimicrobial Suseptibility Testing (EUCAST) website Year-month-date, http://www.eucast.org"

The European Committee on Antimicrobial Susceptibility Testing (EUCAST) has developed the concept of antimicrobial wild type MIC distributions. We have created a software to receive and display large volumes of MIC (Minimum Inhibitory Concentration, mg/L) values of bacteria and fungi over the Internet. It is made freely available to everyone at http://www.eucast.org through EUCAST and ESCMID.

All accepted distributions are displayed in an aggregated format for each species-antibiotic combination. The tables and graphs show only the part of the MIC distribution which  by EUCAST has been defined as the wild type distribution. The epidemiological cut-off value separates microorganisms without (wild type) and with acquired resistance mechanisms (non-wild type) to the drug in question. The epidemiological cut-off value, when defined, is shown in the bottom left-hand corner of each graph in the form WT<X mg/L (less-than-or-equal-to X mg/L)

The wild type MIC distributions are to provide

1. reference material for committees involved in decisions on clinical breakpoints
2. reference material for epidemiological cut-off values for antimicrobial resistance surveillance,
3. reference MIC ranges of wild type organisms for a wide spectrum of species and antimicrobials;
4. an international reference for calibration of antimicrobial susceptibility testing methods.

Each reference distribution is the result of aggregated MIC data where the individual MIC distributions were obtained from publications in international journals, from national breakpoint committees, reference laboratories,  from international antimicrobial surveillance systems such as EARSS (www.earss.rivm.nl), SENTRY, the Alexander Project, MYSTIC, the German Network for Antimicrobial Resistance Surveillance (GENARS), the British Society of Antimicrobial Chemotherapy resistance surveillance program,  other national networks for antimicrobial surveillance, from pharmaceutical companies and from antimicrobial susceptibility testing device manufacturers and from veterinarian surveillance programmes. Thus, unless otherwise specifically stated, the data is representative of results obtained with many different methods. These methods do not give exactly the same results but the results rarely vary by more than one doubling dilution step. In this way the aggregated MIC distributions displayed in the EUCAST software contain the natural random variation between different investigators and the systematic variation seen between different methods. Provided the local resistance frequency is not high an investigator who compares the local MIC distribution with the reference distribution should be able to identify the wild type population in the local data (at least 100 strains need to be investigated) as a distribution with the same median MIC and the same or smaller MIC range as the reference. This validates the local data. If local data do not fit the general distribution of the EUCAST reference distribution it can usually be explained by one of the following:

• MIC determination not adequately calibrated
• Inadequate species identification
• Too few determinations to allow identification of the part of the distribution that corresponds to the wild type microorganisms (number of isolates too low or the proportion of resistant microorganisms too large).

Which MIC determination methods are represented?

Has data obtained with a specific method been excluded?

Why are only MICs of wild type bacteria displayed?

The distributions consist of MIC determinations performed over 30 years or more. While the wild type distribution does not change there may be major differences in resistance over time and between sources. Resistance frequencies obtained through the aggregated MIC distributions would not be representative of current antimicrobial resistance frequencies and would be both confusing and misleading. Thus once the epidemiological cut-off value has been determined by the EUCAST Steering Committee it blocks display of the non-wild type microorganisms.

What is the origin of the organisms included in the MIC data?

What does "Data not released for public use" imply?

When using the software many of the antimicrobials in the pulldown list are followed by the text "data not released for public use". This implies that the software contains data for the drug in question but that it is not complete and that the EUCAST Steering Committee has so far not decided on epidemiological cut-off values.

The EUCAST Steering Committee is in the process of defining epidemiological cut-off values for microbiological resistance and also is working on harmonizing European clinical breakpoints for existing antibiotics. The process of harmonizing clinical breakpoints across Europé and of defining the epidemiological cut-off values for the detection of acquired resistance is co-ordinated with the collection of relevant MIC data. As decisions on breakpoints are made for each group of antibiotics the data, including epidemiological cut-off values and European clinical breakpoints, are released for public use.

Everyone is invited to to contribute data!

Anyone with full-range MIC data for bacteria or fungi is invited to contribute data as long as MICs are determined with a standardized method, which should be named. Once entered on the database the data will not be identifiable as separate distributions but will help build the aggregate reference distributions. The biologically resistant (non-wild type) part of the distribution will be seen only by the EUCAST Steering Committee. Submitting data to the EUCAST data base does not interfere with publication of data.

Where can I get more information?

To the program!