Division 4.2 Method for further characterisation and classification of Salmonella spp. and E. coli isolates showing resistance to third-generation cephalosporins or meropenem
United Kingdom
All presumptive ESBL- or AmpC- or carbapenemase-producing E. coli isolates identified through the selective plating described in point 4.1 as well as all those randomly selected isolates of Salmonella spp. and E. coli that after testing with the first panel of antimicrobials in accordance with Table 1, are resistant to cefotaxime or ceftazidime or meropenem, shall be further tested with a second panel of antimicrobial substances in accordance with Table 4. This panel includes cefoxitin, cefepime and clavulanate synergy test in combination with cefotaxime and ceftazidime for detection of ESBL and AmpC production. In addition the second panel also contains imipenem, meropenem and ertapenem to phenotypically verify the presumptive carbapenemase-producers.
Table 4
Panel of antimicrobial substances, EUCAST epidemiological cut-off values (ECOFFs) and clinical resistance breakpoints and concentrations ranges to be used for testing only Salmonella spp. and indicator commensal E. coli isolates resistant to cefotaxime or ceftazidime or meropenem — (Second panel)
EUCAST epidemiological cut-off values. | ||||
EUCAST clinical resistance breakpoints. | ||||
4 mg/L clavulanic acid. | ||||
The values shall be compared to the values of Cefotaxime and Ceftazidime and interpreted according to CLSI or EUCAST guidelines regarding synergy testing. | ||||
| NA not available. | ||||
| Antimicrobial | Species | Interpretative thresholds of AMR(mg/L) | Range of concentrations (mg/L)(No of wells in brackets) | |
|---|---|---|---|---|
| ECOFFf1 | Clinical breakpointf2 | |||
| Cefoxitin | Salmonella | > 8 | NA | 0,5-64 (8) |
| E. coli | > 8 | NA | ||
| Cefepime | Salmonella | NA | NA | 0,06-32 (10) |
| E. coli | > 0,125 | > 4 | ||
| Cefotaxime + clavulanic acidf3 | Salmonella | NAf4 | NA | 0,06-64 (11) |
| E. coli | NA | NA | ||
| Ceftazidime + clavulanic acid | Salmonella | NA | NA | 0,125-128 (11) |
| E. coli | NA | NA | ||
| Meropenem | Salmonella | > 0,125 | > 8 | 0,03-16 (10) |
| E. coli | > 0,125 | > 8 | ||
| Temocillin | Salmonella | NA | NA | 0,5-64 (8) |
| E. coli | NA | NA | ||
| Imipenem | Salmonella | > 1 | > 8 | 0,12-16 (8) |
| E. coli | > 0,5 | > 8 | ||
| Ertapenem | Salmonella | > 0,06 | > 1 | 0,015-2 (8) |
| E. coli | > 0,06 | > 1 | ||
| Cefotaxime | Salmonella | > 0.5 | > 2 | 0,25-64 (9) |
| E. coli | > 0,25 | > 2 | ||
| Ceftazidime | Salmonella | > 2 | > 4 | 0,25-128 (10) |
| E. coli | > 0,5 | > 4 | ||
Annotations
Footnotes
- f1
EUCAST epidemiological cut-off values.
- f2
EUCAST clinical resistance breakpoints.
- f3
4 mg/L clavulanic acid.
- f4
The values shall be compared to the values of Cefotaxime and Ceftazidime and interpreted according to CLSI or EUCAST guidelines regarding synergy testing.