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Title: Molecular typing of Streptococcus agalactiae isolates from fish

Author
item OLIVARES-FUSTER, OSCAR - AUBURN UNIVERSITY
item KLESIUS, PHILLIP
item EVANS, JOYCE
item ARIAS, COVADONGA - AUBURN UNIVERSITY

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2007
Publication Date: 4/1/2008
Citation: Olivares-Fuster, O., Klesius, P.H., Evans, J.J., Arias, C.R. 2008. Molecular typing of Streptococcus agalactiae isolates from fish. Journal of Fish Diseases. 31(4):277-283.

Interpretive Summary: The genetic variability among Streptococcus agalactiae isolates was assessed. A total of 49 S. agalactiae cultures isolated from different fish species and geographic origins. The S. agalactiae isolates were divided into five distinct genotypes. Genotype 1 grouped all Kuwait isolates while genotype 4 clustered the majority of non-Kuwait isolates (USA, Brazil and Honduras). Genetic differences between S. agalactiae isolates from fish. The result provided valuable information on S. agalactiae genogroups and their geographic origin. The methods are useful for tracking streptococcal disease genogroups around the world.

Technical Abstract: The genetic variability among Streptococcus agalactiae isolates recovered from fish was characterized using single-stranded conformation polymorphisms (SSCP) analysis of the intergenic spacer region (ISR), and amplified fragment length polymorphism (AFLP) fingerprinting. A total of 49 S. agalactiae cultures isolated from different fish species and geographic origins as well as related reference strains were included in the study. ISR-SSCP divided the S. agalactiae isolates analyzed into five distinct genotypes. Genotype 1 grouped all Kuwait isolates while genotype 4 clustered the majority of non-Kuwait isolates (USA, Brazil and Honduras). AFLP analysis offered a higher resolution level by dividing the isolates into 15 different genotypes. Up to three different AFLP profiles were identified within the Kuwait isolates. When data from both ISR-SSCP and AFLP were combined through a multidimensional analysis (MDS), a good correlation between geographic origin and genotypes was observed. Both AFLP and ISR-SSCP revealed genetic differences between S. agalactiae isolates from fish. While AFLP offered a higher resolution, ISR-SSCP also provided valid information being a simpler and faster method. Overall, both methods were in good agreement, showing a correlation between S. agalactiae genogroups and geographic origin.