Related Experiment Video

Updated: Dec 13, 2025

Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
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A novel community-acquired MRSA clone, USA300-LV/J, uniquely evolved in Japan

Shunsuke Takadama1, Hidemasa Nakaminami1, Hiroshi Kaneko1

  • 1Department of Microbiology, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.

The Journal of Antimicrobial Chemotherapy
|July 27, 2020
PubMed
Abstract

Insights

A novel Panton-Valentine leucocidin (PVL)-positive community-acquired MRSA (CA-MRSA) clone, USA300-LV/J, has emerged in Japan. This clone, distinct from USA300, shows unique mobile genetic elements and likely originated abroad.

Area of Science:

  • Microbiology
  • Genomics
  • Epidemiology

Background:

  • USA300 is a significant Panton-Valentine leucocidin (PVL)-positive community-acquired Methicillin-Resistant Staphylococcus aureus (CA-MRSA) clone.
  • USA300 strains are characterized by staphylococcal cassette chromosome mec type IVa (ST8-IVa) and arginine catabolic mobile element (ACME) positivity.
  • USA300-like strains lacking ACME and possessing ST8-IVc were identified in Japan.

Purpose of the Study:

  • To investigate the evolutionary origins and genomic characteristics of USA300-like strains identified in Japan.
  • To determine the phylogenetic relationship of these novel strains to known USA300 clones.

Main Methods:

  • Whole-genome sequencing of a representative USA300-like strain.
  • Comparative genomic analysis using bioinformatics tools like Type Strain Genome Server, MUSCLE, and progressiveMauve.

Main Results:

  • Phylogenetic analysis revealed the USA300-like strain is more closely related to the USA300-Latin American variant (USA300-LV) than to the original USA300.
  • The strain lacked ACME but contained copper and mercury resistance mobile elements.
  • A unique mobile genetic element, ICE6013, was identified, leading to the designation of the novel variant as USA300-LV/J.

Conclusions:

  • The PVL-positive CA-MRSA USA300-LV/J clone represents a novel variant with distinct genomic features.
  • Evidence suggests this clone originated internationally and has undergone unique evolution and dissemination within Japan.

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