Development of a PCR-based method for the detection of Listonella anguillarum in fish tissues and blood samples.

A PCR assay for detection and identification of the fish pathogen Listonella anguillarum was developed. Primers amplifying a 519 bp internal fragment of the L. anguillarum rpoN gene, which codes for the factor sigma54, were utilized. The detection limit of the PCR using L. anguillarum pure cultures was approximately 1 to 10 bacterial cells per reaction. For tissue or blood samples of infected turbot Scophthalmus maximus, the detection limit was 10 to 100 L. anguillarum cells per reaction, which corresponds to 2 x 10(3) to 2 x 10(4) cells g(-1) fish tissue. Our results suggest that this PCR protocol is a sensitive and specific molecular method for the detection of the fish pathogen L. anguillarum.