Edwardsiella ictaluri as the causative agent of mortality in cultured nile tilapia

Esteban Soto Martinez, Matt Griffin, Maziel Arauz, Andres Riofrio, Alexis Martinez, Maria Eugenia Cabrejos

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Edwardsiella ictaluri was consistently isolated from the spleens, livers, and head kidneys of diseased Nile tilapia Oreochromis niloticus from a farm experiencing mortality events in several culture ponds. We describe the first published outbreak of E. ictaluri-induced edwardsiellosis in Nile tilapia. Pure cultures of the isolated bacteria were characterized both biochemically and molecularly. Biochemical analysis was performed using the API-20E and RapID One systems, and antimicrobial susceptibility was determined by the broth microdilution method. Molecular analysis involved sequencing of the 16S rRNA gene, species-specific real-time polymerase chain reaction (PCR), and PCR-mediated genomic fingerprinting (rep-PCR). Pairwise sequence analysis of the 16S rRNA gene identified the case isolates to be a 100% match to E. ictaluri cultured from channel catfish in the southeastern United States. However, rep-PCR analysis identified the case isolates to be genetically different from representative strains isolated from disease outbreaks in cultured channel catfish inMississippi. Infectivity challenges (intraperitoneal injection and immersion) demonstrated that a representative E. ictaluri strain isolated from tilapia was pathogenic to näi{dotless}ve tilapia, reproducing clinical signs and mortality, thereby establishing Koch's postulates.

Original languageEnglish (US)
Pages (from-to)81-90
Number of pages10
JournalJournal of Aquatic Animal Health
Issue number2
StatePublished - 2012
Externally publishedYes

ASJC Scopus subject areas

  • Aquatic Science


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