Identification by a multiplex PCR-based assay of Salmonella typhimurium and Salmonella Enteritidis strains from environmental swabs of poultry houses

A multiplex-PCR-based assay (m-PCR) was developed for the detection of Salm onella and for the identification of the two serotypes Enteritidis and Typh imurium. Three sets of primers selected from different genomic sequences am plified a 429 bp fragment specific for the genus Salmonella within a random ly cloned sequence, a 559 bp target specific for Salmonella Typhimurium wit hin 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 Salmone lla from 1078 environmental swabs of poultry houses. Prior to PCR, these sw abs were pre-enriched in phosphate-buffered peptone water for 18-20 h and t hen sub-cultured on a Modified Semi-solid Rappaport Vassiliadis medium (MSR V) 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 bact eriological method had an agreement rate of 95.6%.