Expert rules and intrinsic resistance

Expert rules and intrinsic resistance

EUCAST expert rules are a tabulated collection of expert knowledge on intrinsic resistances, exceptional resistance phenotypes and interpretive rules that may be applied to antimicrobial susceptibility testing in order to reduce errors and make appropriate recommendations for reporting particular resistances.


EUCAST Expert rules, intrinsic resistance and exceptional phenotypes v 3.1 (Sept 27, 2016)
There are parts of the original document which is not yet covered by the revision. For these the original document (EUCAST Expert rules v 2.0) is valid until the review has been completed.


Expert rules are under revision. The next version will be available as separate tables for each species/species group. The revision is expected to be finalised during 2018. One example is given below for Staphylococcus.



Pseudomonas aeruginosa 

Stenotrophomonas maltophilia

Acinetobacter spp.

Staphylococcus spp.

Enterococcus spp.

Streptococcus A, B, C and G

Streptococcus pneumoniae 

Viridans Group Streptococci

Haemophilus influenzae 

Moraxella catarrhalis 

Neisseria gonorrhoeae

Neisseria meningitidis

Anaerobes, grampositive

Clostridium difficile

Anaerobes, gramnegative

Helicobacter pylorii

Listeria monocytogenes

Pasteurella multocida 

Campylobacter jejuni and C.coli 

Corynebacterium spp.  

Aerococcus sanguinicola and urinae

Kingella kingae

Aeromonas spp.

Mycobacterium spp.




The EUCAST Expert Rules document was subjected to wide consultation during 2016. External comments and Steering Committee and Subcommittee responses are published.



EUCAST Expert rules (version 2.0 valid until Sept 10, 2016)

EUCAST Expert rules (version 1.0 valid until 29 Oct, 2011)