Identification of Pseudomonas anguilliseptica isolated from several fish species in France

Since 1990, outbreaks of haemorrhagic septicemia, frequently associated with keratitis, have occurred on gilthead sea bream Sparus aurata, farmed along the French Mediterranean and Atlantic coasts. Several bacterial isolates obtained from diseased sea bream, sea bass Dicentrarchus labrax, and turbot Scophthalmus maximus showed phenotypic similarities with the Pseudomonas anguilliseptica Wakabayashi & Egusa, 1972 type strain NCIMB 1949 super(T). The French isolates were compared with the type strain by determining levels of deoxyribonucleic acid (DNA) relatedness (S1 nuclease method), guanine + cytosine content (thermal denaturation method), and by performing phenotypic tests. All of the isolates formed a tight genomic species with higher than 90% DNA relatedness to the type strain. This study demonstrates the phenotypic and genomic homogeneity of P. anguilliseptica and confirms that this bacterial species exhibits no host specificity. It thus represents a potential hazard for many farmed fish species and could cause serious economic losses.