Multiplex PCR assay (m-PCR) with three sets of primers was developed for simultaneous identification of Campylobacter jejuni and C. coli. Poultry faecal samples were enriched in Preston broth for 24 h and streaking on selective media was performed before and after enrichment. m-PCR was applied on bacterial cultures harvested from media plates. The data showed a selective effect of Preston broth which favoured the growth of C. coli. Identification of the species by the hippurate hydrolysis test and by the m-PCR was performed on 294 isolates of Campylobacter. The efficiency of the identification by the biochemical test is only 34% in comparison to 100% efficiency with the PCR. The use of our m-PCR in combination with the culture method allowed reliable detection and identification of C. jejuni and C. coli within 3-4 d.

A Multiplex PCR-based assay (m-PCR) with three sets of primers was developed for the detection of all serotypes of Salmonella enterica and the identification of Salmonella Enteritidis and Salmonella Typhimurium. This method was evaluated against a bacteriological method for the analysis of environmental swabs of poultry houses. Samples were preenriched in phosphate-buffered peptone water for 24 h and subjected to three different protocols prior to PCR: (i) an immunomagnetic separation using Dynabeads TM anti-Salmonella (Dynal); (ii) a DNA extraction procedure using the Instagene TM matrix; (iii) an additional step of culture on an MSRV medium. With protocols 1 and 2, eight positive results were found by PCR and 20 with the bacteriological method. Protocol 3 combining MSRV and PCR gave similar results to those obtained from bacteriological methods and allowed Salmonella detection within 2 days.

A multiplex-PCR-based assay (m-PCR) was developed for the detection of Salmonella and for the identification of the two serotypes Enteritidis and Typhimurium. Three sets of primers selected from different genomic sequences amplified a 429 bp fragment specific for the genus Salmonella within a randomly cloned sequence, a 559 bp target specific for Salmonella Typhimurium within the fliC gene and a 312 bp fragment specific for Salmonella Enteritidis within the sefA gene. The m-PCR-based assay was used for detecting Salmonella from 1078 environmental swabs of poultry houses. Prior to PCR, these swabs were pre-enriched in phosphate-buffered peptone water for 18-20 h and then sub-cultured on a Modified Semi-solid Rappaport Vassiliadis medium (MSRV) for 18-20 h. The m-PCR combined with MSRV had a better sensitivity (95%) than the bacteriological method (92·5%). The MSRV-m-PCR assay and the bacteriological method had an agreement rate of 95·6%.

Colistin resistance was investigated in 1,696 isolates collected from 2007 to 2014 within the frame of the French livestock antimicrobial resistance surveillance programme. The mcr-1 gene was detected in all commensal Escherichia coli isolates with a minimum inhibitory concentration to colistin above the 2 mg/L cut-off value (n=23). In poultry, mcr-1 prevalence was 5.9% in turkeys and 1.8% in broilers in 2014. In pigs, investigated in 2013, this prevalence did not exceed 0.5%. These findings support that mcr-1 has spread in French livestock.