Novel PCR assay for identification of Salmonella enterica serovar Infantis

Aims: We developed, optimized and tested two novel PCR assays specific for Salmonella enterica subspecies enterica serovar Infantis. Methods and Results: The fljB gene was chosen as the target sequence. Primers were designed on a consensus sequence built by sequencing the fljB gene of five genetically unrelated Hungarian S. Infantis strains and using sequence data from the GenBank (http://www.ncbi.nih.gov). Two alternative assays were designed, which share the reverse primer. Both proved to be highly specific to S. Infantis, neither reacted with 42 other nontyphoidal serovariants tested. The detection limit of the assays was determined to be 10(5) CFU ml(-1) from pure culture, and 10(6) CFU g(-1) from artificially spiked chicken faeces samples. Conclusion: Although the detection limit is rather high to allow for using them for direct detection, the assays may be useful in identification of S. Infantis both for diagnostic and for research purposes. Significance and Impact of the study: The described PCR assays allow for the correct identification of S. Infantis even when traditional serotyping methods fail because lack of expression of flagellar antigens.