Genotyping of S. agalactiae strains isolated from human, bovine and fish and their virulence potential to Nile tilapia / Genotipagem de Streptococcus agalactiae isolados de seres humanos, bovinos e peixes e seu potencial de virulÃncia para tilÃpia do Nilo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Streptococcus agalactiae (Lancefield group B; GBS) is an important pathogen to human, bovine and fish causing neonatal sepsis, mastitis and meningo-encephalitis, respectively. The objective of this study was to characterize by PFGE S. agalactiae isolated from fish (n=27), bovine (n=9) and human (n=11) and to investigate the virulence of bovine, fish and human strains to Nile tilapia (Oreochromis niloticus). The fish strains were isolated from nine Nile tilapia farms, the bovine strains from nine dairy cow farms and human strains from distinct clinical outcomes. The PFGE types were determined by dendogram analyses and the in vivo virulence was evaluated by experimental infection (using i.p and immersion routes) in Nile tilapia. Among fish strains five different PFGE patterns were observed, including the occurrence of two or three profiles in the same farm. Twenty one of twenty seven strains isolated from fish showed the same genetic pattern (predominant pattern). To bovine and human strains high genetic diversity were observed, but no relations were established to the three host sources analyzed. Regarding the infectivity to Nile tilapia, three bovine strains were able to infect fish (by i.p.route) and two of those strains caused clinical signs of meningoencephalitis. All human strains (n= 5) submitted to experimental infection were able to infect Nile tilapia and clinical disease was induced by one strain (80427). This isolate was also able to infect Nile tilapia by immersion route and induce clinical signs. Eight fish strains of S. agalactiae, belonged to different PFGE types, caused high mortality in Nile tilapia. In conclusion the analyzed strains from the three natural hosts did not show genetic relatedness and, in spite of that, some bovine and human strains were able to infect fish and cause meningoencephalitis. We suggest that these strains share some virulence factors and that genetic linkage is not a prerequisite to S. agalactiae to cross the host-specific barrier.

ASSUNTO(S)

s. agalactiae, fish, human, bovine, pfge medicina veterinaria streptococcus agalactiae pfge peixe

ACESSO AO ARTIGO

Documentos Relacionados