Submitted to: European Association of Fish Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 6/4/2007
Publication Date: 9/17/2007
Citation: Evans, J.J., Bohnsak, J., Klesius, P.H., Whiting, A.A., Garcia, J.C., Shoemaker, C.A. 2007. Genomic diversity of streptococcus agalactiae from fish, bovine and human hosts. page 131. European Association of Fish Pathologists. 13th EAFP International Conference on 'Disease of Fish and Shellfish' 17th-21st September, 2007 Grado, Italy. Interpretive Summary:
Technical Abstract: Group B Streptococcus agalactiae (GBS) is a cause of infectious disease in multiple poikilothermic and homothermic animal species. Epidemiological and zoonotic considerations necessitate an undertaking of a comparison of S. agalactiae isolates from different phylogenetic hosts and geographical regions. Intraspecific and interspecific variations in piscine GBS isolates have not been explored. Futhermore, interspecific differences between piscine and human and bovine GBS reference strains have not been explored. This study examined the genetic relatedness among these GBS strains using serological and multilocus sequence typing (MLST) molecular techniques and compared these to non-fish GBS isolates in the GBS MLST database (http://sagalactiae.mlst.net). A previously unreported piscine capsular serotype, Ia, was discovered for isolates originating from Kuwait, Brazil, Israel and the U.S.A. An isolate from Honduras and another Israeli isolate were nontypable. Sequence typing of piscine isolates produced five sequence types (ST-7, ST-257, ST-258, ST-259 and ST-260), the latter four ST’s representing allelic designations and allelic combinations previously undescribed in the S. agalactiae MLST database. Kuwait piscine GBS isolates from mullet and seabream appear to share a common ancestry (Ia ST-7). Although largely unrelated to the majority of human GBS strains, Kuwait GBS fish isolates share sequence type, capsular serotype and biochemical profile with six GBS isolates from human sources in Japan (three from infected neonates and three from colonized adults) indicating their potential to cause human GBS disease or originate from human sources. Genomic diversity existed between piscine GBS isolates from Kuwait and other geographical areas. Piscine GBS isolates from Brazil, Israel, Honduras and the U.S.A. appear to be part of a clonal complex and are unrelated to human and bovine GBS, thus representing a distinct genetic population or genotype. Comparative genomics of piscine, human and bovine GBS could help clarify those genes important for host tropism, emergence of unique pathogenic clones, and whether these hosts act as reservoirs for another hosts’ pathogenic lineages.