ECDC targets AMR data quality and comparability

The European Committee on Antimicrobial Susceptibility Testing (EUCAST) is determining, reviewing and revising European clinical breakpoints and epidemiological cut-off values for antimicrobial susceptibility testing for antimicrobials used to treat human infections.

The protocol for monitoring of AMR in Salmonella and Campylobacter from human isolates aims to increase quality and comparability of AMR data collected at EU level from different Member States, said the European Centre for Disease Prevention and Control (ECDC) in the technial document​.

Testing guidance​

It is primarily targeted to the National Public Health Reference Laboratories to guide the susceptibility testing needed for EU surveillance and the reporting to ECDC.

It also provides guidance on how to improve comparison of results with the AMR monitoring performed in isolates from animals and food products.

ECDC started work on harmonisation of AMR surveillance for zoonotic bacteria in human infections in 2012 and an EU protocol for Salmonella and Campylobacter infections was published in March 2014, after consultations with the Food- and Waterborne Diseases and Zoonoses (FWD) network.

The Commission decision 2013/652/EU on the monitoring and reporting of antimicrobial resistance in zoonotic and commensal bacteria entered into force 1 January 2014.

It mostly corresponds to the updated ECDC protocol but some differences exist in the panel of antimicrobials to be tested.

A priority list of antimicrobial agents to monitor for surveillance purposes includes eleven antimicrobial substances for Salmonella and four for Campylobacter.

Antimicrobial measurement​

For laboratory measurement of antimicrobial activity the EUCAST method is recommended.

Additional detail is given regarding methods for detection and confirmation of two specific resistance phenotypes of particular concern – extended-spectrum beta-lactamase (ESBL) producers and carbapenemase producers.

Disk diffusion is most widely used for measurement of antimicrobial activity against Salmonella (inhibition zone diameters (IZD) expressed in mm) in routine clinical laboratories.

Dilution methods where the minimum inhibitory concentration (MIC) is determined (value expressed in mg/L) is a more accurate measurement and is considered the gold standard for AST.

Micro-broth dilution is recommended as the preferred testing method for monitoring purposes, said ECDC.

ECDC encouraged Member States to submit results of susceptibility testing as ‘quantitative’ values (minimum inhibitory concentration in mg/L or zone diameter in mm) instead of qualitative results (SIR).

This facilitates comparison of data over time, and to allow comparison with quantitative AMR data from animal and food isolates that takes account of epidemiological cut-off values for the relevant bacterial species.

The agency added quantitative AMR data for Salmonella and Campylobacter can be reported to it through the SALMISO and CAMPISO record types which allow laboratories to report isolate-based AMR data to TESSy, either via BioNumerics or as CSV files.

Meanwhile, the first report from the EUCAST subcommittee on the role of whole genome sequencing (WGS) in antimicrobial susceptibility testing has been published​. It is open for comments until 24 June.