title: Identification and virulence of Aeromonas dhakensis, Pseudomonas mosselii and Microbacterium paraoxydans isolated from Nile tilapia, Oreochromis niloticus, cultivated in Mexico.
abstract: OBJECTIVE
  To identify bacterial pathogens of diseased NiIe tilapia Oreochromis niloticus and determine their virulence.
  
  
  RESULTS
  Sixteen bacterial isolates were recovered from diseased Nile tilapias (O. niloticus) reared in floating cages in Adolfo Lopez Mateos (ALM), Sanalona and Dique IV dams in Sinaloa, Mexico, from February to May 2009. The bacterial isolates were identified by phenotypic and molecular (rep-PCR and 16S rRNA sequencing) methods and were mostly isolated from the kidneys and the brain of tilapias. Bacterial cells and extracellular products (ECPs) of strains were characterized and used in experimental infections with sole Solea vulgaris and Mozambican tilapia Oreochromis mossambicus. The fish challenged with Aeromonas dhakensis sp. nov. comb nov, Pseudomonas mosselii and Microbacterium paraoxydans (3·1 × 10(6)  CFU g(-) 1) exhibited mortality between 40 and 100% starting at 6 h postinoculation. The ECPs displayed gelatinase, haemolytic and cytotoxic activity, causing the total destruction of the HeLa cell lines.
  
  
  CONCLUSIONS
  Aeromonas dhakensis and Ps. mosselii were virulent to O. mossambicus, whereas Mic. paraoxydans displayed virulence to S. vulgaris.
  
  
  CONCLUSIONS
  This the first time that Aeromonas dhakensis and Ps. mosselii are reported as pathogens to tilapia and Mic. paraoxydans was isolated from fish; then, these fish pathogens could be a threat to farmed Nile tilapia in Mexico.
authors.affiliation: CIAD, A.C. Mazatlan Unit for Aquaculture and Environmental Management, Mazatlan, Sinaloa, Mexico. ssoto@ciad.mx
authors.forename: S A
authors.initials: SA
authors.lastname: Soto-Rodriguez
authors.forename: J
authors.initials: J
authors.lastname: Cabanillas-Ramos
authors.forename: U
authors.initials: U
authors.lastname: Alcaraz
authors.forename: B
authors.initials: B
authors.lastname: Gomez-Gil
authors.forename: J L
authors.initials: JL
authors.lastname: Romalde
mesh_terms: D000192:Actinomycetales / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D000333:Aeromonas / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D000818:Animals; D023681:Cichlids / Q000382:microbiology*; D005393:Fish Diseases / Q000382:microbiology / Q000401:mortality; D006367:HeLa Cells; D006801:Humans; D008800:Mexico; D011549:Pseudomonas / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014774:Virulence
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: Aeromonas dhakensis; Microbacterium paraoxydans; Nile tilapia; Pseudomonas mosselii; cage culture; fish pathogen