Submitted to: Journal of Medical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2008
Publication Date: 11/1/2008
Citation: Evans, J.J., Bohnsack, J.F., Klesius, P.H., Whiting, A.A., Garcia, J.C., Shoemaker, C.A. Takahashi, S. 2008. Phylogenetic relationships among Streptococcus agalactiae isolated from piscine, dolphin, bovine and human sources: a dolphin and piscine lineage associated with a fish epidemic in Kuwait is also associated with human neonatal infections in Japan. Journal of Medical Microbiology. 57(11):1369-1376. Interpretive Summary: Despite being known mainly as a mammalian animal disease agent, S. agalactiae has become recognized as an emerging pathogen of wild and cultured fish and bottlenose dolphins. This study examined the genetic relatedness of piscine, dolphin, and human S. agalactiae isolates and bovine S. agalactiae reference strains from different geographical regions using serological and multilocus sequence typing (MLST) molecular techniques. The Kuwait dolphin and piscine lineage (Sequence type-7, serotype Ia) is also associated with human neonatal infections in Japan. These findings suggest that isolates derived from different animal species have the potential to cause disease in humans.
Technical Abstract: Group B Streptococcus agalactiae (GBS) causes of infections in multiple animals. This study examined the genetic relatedness of piscine, dolphin, and human GBS isolates and bovine GBS reference strains from different geographical regions using serological and multilocus sequence typing (MLST) techniques. Piscine isolates originating from Kuwait, Brazil, Israel and the U.S.A. were capsular serotype, Ia, which has been previously unreported. Sequence typing of piscine isolates produced six sequence types (ST-7, ST-257, ST-258, ST-259, ST-260, and ST-261), the latter five ST’s representing allelic designations and allelic combinations not previously reported in the S. agalactiae MLST database. Genomic diversity exists between dolphin and piscine GBS isolates from Kuwait and other geographical areas. Piscine GBS isolates from Brazil, Israel, Honduras and the U.S.A. appear to represent a distinct genetic population of strains that are largely unrelated to human and bovine GBS. The Kuwait dolphin and piscine lineage (ST-7, Ia) is also associated with human neonatal infections in Japan. 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 of one anothers’ pathogenic lineages.