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Table 1 Definition of Gram-negative Multidrug-resistant organisms according to German guideline

From: Cross-border comparison of the Dutch and German guidelines on multidrug-resistant Gram-negative microorganisms

Antibiotic

Enterobacteriaceae, Acinetobacter baumannii

Pseudomonas aeruginosa

 

3MRGN

4MRGN

3MRGN

4MRGN

Piperacillin

R

R

Only one antibiotic group is susceptible

R

Cefotaxime/Ceftazidime

R

R

 

R

Imipenem/meropenem

S

R

 

R

Ciprofloxacin

R

R

 

R

Specifications/exceptions

Count as “R” if one antibiotic of the category is resistant (e.g. imipenem OR meropenem).

Count as “R” if all antibiotics of each category are resistant (e.g. imipenem AND meropenem).

If “R” for imipenem or meropenem, then always report as 4MRGN (irresp. of test result for other antibiotics).

Cefepime can also be considered in addition to ceftazidime.

If carbapenemase is detected, always categorize as 4MRGN.

  1. Definition of Gram-negative Multidrug-resistant organisms (GN-MDRO), designated “MRGN”, is based on results of phenotypic susceptibility testing to four antibiotic classes before the antibiogram is modified by interpretative reading. R = resistant or intermediate; S = susceptible. Enterobacteriaceae are categorized as “3MRGN” (GN-MDRO with resistance to 3 antibiotic classes), if carbapenems are still susceptible and “4MRGN” (GN-MDRO with resistance to 4 antibiotic classes), if not. P. aeruginosa isolates are categorized as “3MRGN” if at least one of the four antibiotic classes is susceptible and “4MRGN”, if all are resistant. Other pheno- or genotypic test results are not considered for the definition with the important exception of carbapenemase production which automatically lead to a classification as “4MRGN”.