Multicentre evaluation of a selective isolation protocol for detection of mcr-positive E. coli and Salmonella spp. in food-producing animals and meat
- By
- Agnes Perrin-Guyomard, Sophie A. Granier, Jannice Schau Slettemeås, Muna F Anjum, Luke Randall, Manal AbuOun, Natalie Pauly, Alexandra Irrgang, Jens Andre Hammerl, Jette Sejer Kjeldgaard, Anette M Hammerum, Alessia Franco, Magdalena Skarzynska, Ewelina Kaminska, Dariusz Wasyl, Cindy Dierikx, Stefan Börjesson, Yvon Guerts, Marisa Haenni, Kees Veldman
This study was conducted to evaluate the performance of a screening protocol to detect and isolate mcr-positive Escherichia coli and Salmonella spp. from animal caecal content and meat samples. We used a multicentre approach involving 12 laboratories from nine European countries. All participants applied the same methodology combining a multiplex PCR performed on DNA extracted from a pre-enrichment step, followed by a selective culture step on three commercially available chromogenic agar plates. The test panel was composed of two negative samples and four samples artificially contaminated with E. coli and Salmonella spp. respectively harbouring mcr-1 or mcr-3 and mcr-4 or mcr-5 genes. PCR screening resulted in a specificity of 100% and a sensitivity of 83%. Sensitivity of each agar medium to detect mcr-positive colistin-resistant E. coli or Salmonella spp. strains was 86% for CHROMID ColistinR, 75% for CHROMagarTM COL-APSE and 70% for COLISTIGRAM. This combined method was effective to detect and isolate most of the E. coli or Salmonella spp. strains harbouring different mcr genes from food-producing animals and food products and might thus be used as a harmonized protocol for the screening of mcr genes in food-producing animals and food products in Europe.