Verification of an Edwardsiella ictaluri-specific diagnostic PCR.

AIMS

To verify the specificity of a PCR assay for the identification and diagnosis of Edwardsiella ictaluri.

METHODS AND RESULTS

An Edwardsiella ictaluri-specific PCR assay was developed utilizing two features of the ribosomal DNA gene clusters. The first feature is the presence of two ribosomal gene clusters located in tandem to one another (the inter-ribosomal spacer, IRS). This characteristic is present in the Edwardsiella genus but absent in the other sequenced members of the Enterobacteriaceae. The second feature is the presence of an intervening sequence (IVS) in the 23S rRNA gene of Edw. ictaluri. To verify the specificity of this assay, we tested genomic DNA from a variety of bacterial species. The IVS/IRS PCR assay results in an c. 2000-bp product from all Edw. ictaluri isolates tested, but not from any other species including Edwardsiella tarda.

CONCLUSIONS

The IVS/IRS PCR assay is highly specific for Edw. ictaluri and useful as a tool for identifying this pathogen.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research verifies the specificity of PCR-based assay for Edw. Ictaluri, and we describe this assay as a highly versatile diagnostic tool for its identification.