Streptococcus iniae E Streptococcus dysgalactiae ASSOCIADOS Ã MENINGOENCEFALITE E SEPTICEMIA EM TILÃPIAS DO NILO NO BRASIL / Streptococcus iniae AND Streptococcus dysgalactiae ASSOICIATED WITH MENINGOENCEPHALITIS AND SEPTICEMIA IN NILE TILAPIA IN BRAZIL

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Pisciculture is a relatively recent branch of agorbussines in Brazil although a large increase has been observed in recent decades Tilapia is the mainly cultivate fish in Brazil in view of the fact that this specie had a great acceptance in the consumer market and large resistance to environment variations The major sources of fish production damage worldwide are streptococcosis Outbreaks caused by Streptococcus stand out by affecting a broad range of hosts in several region of the world The specie S iniae is commonly associated with aquatic animal disease Nowadays it is pointed to as the main pathogen causing millions of dollars in damage annually To date 27 fish species have been related as susceptible to S iniae infection Outbreaks in fish caused by this pathogen are characterized by septicemia and meningoencephalitis Another specie of Streptococcus reported as pathogenic to fish is Streptococcus dysgalactiae This specie is a common pathogen of domestic animals and humans and was recently isolated from outbreaks in cultured fish in Japan This pathogen was related to septicemia and necrotic lesions on the caudal peduncle in the species Seriola dumerili and Seriola quinqueradiata In Brazil both species have never been associated with fish infections before The aim of this study was to identify Streptococcus sp isolated from outbreaks in Nile tilapia farms in Paranà and Cearà states Brazil Beside this access the genetic variability of identified S iniae isolates as well as testing the capacity of identified S dysgalactiae isolate in causing disease in Nile tilapia through experimental infection Characteristically streptococcal outbreaks were accompanied in Nile tilapia farms in Brazil Two proprieties in Paranà 2006 and one in Cearà 2007 were accompanied both in the summer season Bacteriological exams of kidney brain and absceses were carried out in the fish with characteristic clinical signs Isolates were submitted to Gram-stain catalase and oxidase tests Bacterial identification was done phenotypically and genetically through API 20 Strep Slidex species-specific PCR and sequencing The 16S rRNA gene of both species were amplified and sequenced with universal primers The isolates with diagnostic for S dysgalactiae were also submitted to sequencing of the 16S-23S rDNA intergenic spacer region To test the capacity of these isolates to cause disease experimental infection was carried out To access the genetic variability of the isolates identified as S iniae and with the reference strain S iniae ATCC 29178 PFGE was realized All studied farms have high stockages densities 150 Kg/m3 and 300 Kg/m3 in Paranà and Cearà respectively In addition the water temperature was around 30ÂC The phenotypical and molecular tests confirmed the identification of S iniae 7 isolates and S dysgalactiae 10 isolates as the etiological agents of the outbreaks occurred in Paranà and Cearà states respectively The Brazilian S iniae isolates had two distinct genotypes and a third pattern was observed with the type strain S iniae ATCC 29178 Fish challenge showed that S dysgalactiae isolate is able to cause disease with discrete clinical signs but with positive reisolation of kidney and brain

ASSUNTO(S)

morfologia streptococcus iniae streptococcus dysgalactiae tilÃpia do nilo pfge infecÃÃo experimental streptococcus iniae streptococcus dysgalactiae tilÃpia do nilo pfge infecÃÃo experimental

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