Important tools to help you organise and optimise your susceptibility testing results

Susceptibility Testing Template Program to create zone templates

Standardised disc diffusion method involves measuring the diameter of zones of inhibition with a ruler, callipers, or with an automated zone reader; however, zones of inhibition may also be measured in relation to zone templates.

The Renaissance artist Giotto de BonDone was able to draw a perfect circle freehand. The less gifted may use this program (known as Giotto2) to generate their zone templates.

Instructions to access the Susceptibility Testing Template Program:

  • Please click here to download (you can also right click and ‘Save As’)
  • Click to unzip/extract all
  • Run file Giotto2.exe
  • Read help file

If you have any difficulty in accessing the programme, please check the FAQs document and if the problem persists, email Mandy Wootton


How to add templates to controlled documents

Once the templates have been produced many laboratories need to add them to controlled Standard Operating Procedure (SOP) documents.

This document contains instructions for adding templates to controlled Standard Operating Procedures (SOP): How to add templates to controlled documents.


Quality control of Antimicrobial Susceptibility Testing

The following documents may be useful for tracking Internal Quality Control (IQC) data and also diagnosing IQC problems when performing the EUCAST disc diffusion method

This document contains relevant information to help diagnose problems with quality control data: Quality Control Information

To maintain high quality of susceptibility testing results, IQC should be performed either daily or at least 4 times per week. Keep track of your laboratory’s zone diameter IQC data using the QC disc data tracker. This Excel document allows you to track your QC disc diameter data, included is a help file.


Uncertainty of Measurement

All manual susceptibility testing requires reading of inhibition zones or ellipses. To maintain high quality result reporting, all laboratories should assess the ability of staff to measure zone diameters and MICs. These documents describe the natural and human errors within susceptibility testing methods and provide a template for recording Uncertainty of Measurement (UoM):

How to measure UoM in AST

Disc Diffusion UoM Tool

MIC UoM Tool


For help with any of the susceptibility testing tools on this webpage please contact Mandy Wootton

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