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Reclassification of phenotypically identified staphylococcus intermedius strains

Takashi Sasaki1, Ken Kikuchi, Yoshikazu Tanaka

  • 1Department of Infection Control Science, Faculty of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.

Journal of Clinical Microbiology
|June 29, 2007
PubMed

Insights

This study reclassifies Staphylococcus intermedius group (SIG) strains using molecular and phenotypic analyses. Findings reveal distinct clusters corresponding to Staphylococcus pseudintermedius, Staphylococcus intermedius, and Staphylococcus delphini, with evidence for a potentially novel species.

Area of Science:

  • Microbiology
  • Bacterial Taxonomy
  • Molecular Phylogenetics

Background:

  • The Staphylococcus intermedius group (SIG) includes species phenotypically similar but genetically distinct.
  • Accurate classification is crucial for understanding host-pathogen relationships and disease transmission.

Purpose of the Study:

  • To reclassify phenotypically identified SIG strains using molecular and phenotypic data.
  • To differentiate between true Staphylococcus intermedius and closely related species like Staphylococcus pseudintermedius and Staphylococcus delphini.

Main Methods:

  • Phylogenetic analysis of sodA, hsp60, and nuc gene sequences.
  • Phenotypic characterization including biochemical tests (arginine dihydrolase, acid production).
  • DNA-DNA hybridization for strain differentiation.

Main Results:

  • Phylogenetic analysis divided SIG strains into three main clusters: S. pseudintermedius, S. intermedius, and S. delphini.
  • Strains from common hosts (dogs, cats, humans) were identified as S. pseudintermedius.
  • S. delphini strains showed further subdivision (Group A and Group B), with Group B genetically closer to S. pseudintermedius.
  • Biochemical tests could distinguish S. intermedius from S. pseudintermedius/S. delphini, but not between S. delphini groups and S. pseudintermedius.

Conclusions:

  • SIG strains were reclassified into four distinct clusters, representing three established species and one probable novel species.
  • S. pseudintermedius is prevalent in domestic animals and humans.
  • Further investigation is needed to fully characterize the novel S. delphini group B and its taxonomic status.

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