One Health EJP
Published May 20, 2021 | Version v1
Journal article Open

Isolation Procedure for CP E. coli from Caeca Samples under Review towards an Increased Sensitivity

Creators

  • 1. German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung), D-10589 Berlin, Germany
  • 2. State Office for Health and Social Affairs Berlin, D-10639 Berlin, Germany
  • 3. German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung), D-10589 Berlin, Germany; Unit for Veterinary Public Health and Epidemiology, University of Veterinary Medicine, AT-1210 Vienna, Austria
  • 4. Institute of Microbiology and Epizootics, Freie Universität Berlin, D-14163 Berlin, Germany; FAO Reference Centre for Antimicrobial Resistance, Freie Universität Berlin, D-14163 Berlin, Germany
  • 5. Institute of Food Safety and Food Hygiene, Freie Universität Berlin, D-14163 Berlin, Germany

Description

Due to the increasing reports of carbapenemase-producing Enterobacteriaceae (CPE) from
livestock in recent years, the European Reference Laboratory for Antimicrobial Resistances (EURLAR)
provided a protocol for their recovery from caecum and meat samples. This procedure exhibited
limitations for the detection of CPE with low carbapenem MIC values. Therefore, it was modified by a
second, selective enrichment in lysogeny broth with cefotaxime (CTX 1 mg/L) and with meropenem
(MEM 0.125 mg/L) at 37 C under microaerophilic conditions. By Real-time PCR, these enrichments
are pre-screened for the most common carbapenemase genes. Another adaptation was the use of
in-house prepared MacConkey agar with MEM and MEM+CTX instead of commercial selective agar.
According to the EURL-method, we achieved 100% sensitivity and specificity using the in-house
media instead of commercial agar, which decreased the sensitivity to ~75%. Comparing the method
with and without the second enrichment, no substantial influence on sensitivity and specificity was
detected. Nevertheless, this enrichment has simplified the CPE-isolation regarding the accompanying
microbiota and the separation of putative colonies. In conclusion, the sensitivity of the method can
be increased with slight modifications.

Notes

This work was financially supported by a grant of the German Federal Institute for Risk Assessment (43-001 and 43-002). The work of Natalie Pauly was supported by the European Joint Project (EJP) IMPART funded by the European Union's Horizon 2020 research and innovation programme under Grant Agreement No 773830. The work of Stefan Schwarz is supported by the German Federal Ministry of Education and Research (BMBF) under project number and 01KI2009D as part of the Research Network Zoonotic Infectious Diseases.

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Funding

One Health EJP – Promoting One Health in Europe through joint actions on foodborne zoonoses, antimicrobial resistance and emerging microbiological hazards. 773830
European Commission