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Draft genome sequence of a multidrug-resistant Streptococcus agalactiae sequence type 1665 strain isolated from

Saki Kanehira1, Yusuke Ota2, Kazunari Sonobe1

  • 1Department of Clinical Laboratory, Institute of Science Tokyo Hospital, Tokyo, Japan.

Microbiology Resource Announcements
|June 26, 2026
PubMed

Insights

A drug-resistant Streptococcus agalactiae strain was identified, showing resistance to multiple antibiotics including beta-lactams. Genomic surveillance is crucial for managing invasive infections caused by such resistant bacteria.

Area of Science:

  • Microbiology
  • Genomics
  • Infectious Diseases

Background:

  • Streptococcus agalactiae (Group B Streptococcus) is a significant pathogen.
  • Increasing antimicrobial resistance in S. agalactiae complicates treatment and infection control.
  • The potential for invasive disease necessitates ongoing surveillance.

Purpose of the Study:

  • To characterize a novel strain of Streptococcus agalactiae with a concerning resistance profile.
  • To identify genetic determinants contributing to antimicrobial resistance in this strain.
  • To emphasize the importance of genomic surveillance for Streptococcus agalactiae.

Main Methods:

  • Isolation and identification of Streptococcus agalactiae.
  • Antimicrobial susceptibility testing (phenotypic characterization).
  • Whole-genome sequencing to identify genetic mutations and resistance mechanisms, including analysis of PBP2X variants.

Main Results:

  • A sequence type 1665 Streptococcus agalactiae strain was isolated.
  • The strain exhibited nonsusceptibility to beta-lactams and resistance to macrolides, tetracyclines, and fluoroquinolones.
  • Previously uncharacterized variants in the penicillin-binding protein 2X (PBP2X) were identified.

Conclusions:

  • The emergence of multidrug-resistant Streptococcus agalactiae, including beta-lactam nonsusceptibility, poses a significant public health threat.
  • Genomic surveillance is essential for early detection of resistant strains and informing clinical treatment strategies.
  • Understanding resistance mechanisms, such as novel PBP2X variants, is critical for effective infection control and guiding antimicrobial therapy.
Keywords:
ascitic fluiddraft genome sequencemultidrug-resistant Streptococcus agalactiae

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