Serotype III Streptococcus agalactiae from bovine milk and human neonatal infections

Emerg Infect Dis. 2004 Aug;10(8):1412-9. doi: 10.3201/eid1008.030917.


Streptococcus agalactiae (group B streptococcus [GBS]) causes invasive human infections and bovine mastitis. This study examined the genetic relationship between bovine and human serotype III GBS by using molecular techniques that classify human serotype III GBS into four distinct phylogenetic lineages. Bovine serotype III GBS were largely contained in two lineages, which are distinct from the two major lineages (restriction digest types III-2 and III-3) that infect human neonates. One of the bovine lineages closely resembles the human III-1 lineage, whose members occasionally cause human neonatal infections. The bovine strains in the other lineage characteristically have an initiation factor IF2 gene (infB) H allele and multilocus sequence types that are not found in human GBS strains. Evidence suggests that this "H allele" lineage is related to the human III-3 lineage. These results support the assertion that human and bovine GBS are largely unrelated and provide further insight into the genetic relation between human and bovine GBS.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Animals
  • Cattle
  • Cattle Diseases / microbiology*
  • Female
  • Humans
  • Infant, Newborn
  • Milk / microbiology*
  • Molecular Sequence Data
  • Pregnancy
  • Pregnancy Complications, Infectious / microbiology*
  • Prokaryotic Initiation Factor-2 / genetics
  • Random Amplified Polymorphic DNA Technique
  • Sequence Analysis, DNA
  • Serotyping
  • Streptococcal Infections / microbiology*
  • Streptococcus agalactiae / classification*
  • Streptococcus agalactiae / genetics*


  • Prokaryotic Initiation Factor-2

Associated data

  • GENBANK/AY429663
  • GENBANK/AY437915