Visceral granulomas in farmed large yellow croaker, Larimichthys crocea (Richardson), caused by a bacterial pathogen, Pseudomonas plecoglossicida

An enzootic disease characterized by granulomas in internal organs occurred in cage‐farmed large yellow croaker, L arimichthys crocea ( R ichardson), in A pril and N ovember 2010, in N ingbo, Z hejiang P rovince. One bacterial strain, named XSDHY‐P, was isolated from the diseased fish and identified by biochemical characterization, fatty acid methyl ester ( FAME ) analysis and multilocus sequence analysis ( MLSA ). According to the results obtained from the biochemical tests, FAME analysis and phylogenetic analysis derived from 16S ribosomal RNA , gyrB , oprF , oprI , oprL and rpoD gene sequencing, the bacterial isolate, XSDHY‐P , was identified as P seudomonas plecoglossicida . Moreover, lethal dose, 50% trials were carried out to demonstrate the virulence of XSDHY‐P in large yellow croaker when administered at 2.13 × 10 5  colony‐forming units per fish. Visceral granulomas were found in the experimentally infected fish as well as in the naturally infected fish, indicating that P . plecoglossicida is another bacterial pathogen that causes granulomatosis in L .  crocea .