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Updated: Jul 29, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Emergence of community-associated methicillin-resistant Staphylococcus aureus ΨUSA300 among Japanese people with HIV,
Koh Shinohara1,2, Yuki Uehara3,4, Katsuji Teruya1
1AIDS Clinical Center, The National Center for Global Health and Medicine, Tokyo, Japan.
Abstract:
Although infection with the methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 is extremely rare in Japan, the uniquely evolved clone ΨUSA300 has been reported in Japan. An outbreak of a distinct USA300 clone was recently reported in an HIV/AIDS referral hospital in Tokyo. The present study investigated the evolutionary origin and genetic diversity of USA300-related clones causing regional outbreaks among people living with HIV (PLWHIV) in Tokyo. MRSA isolates collected from PLWHIV in an HIV/AIDS referral center in Tokyo were subjected to whole-genome sequencing and their genetic features were compared with those of previously described USA300 MRSA genomes. Of the 28 MRSAs isolated in 2016-2019, 23 (82.1%) were identified as USA300, with 22 (95.6%) of the latter identified as ΨUSA300. Although the genomic structure of ΨUSA300 was identical to the structures of reference USA300 strains, one clade (cluster A) was found to have acquired 29 previously identified lineage-specific mutations in a stepwise manner. The estimated divergence dates of ΨUSA300 and Cluster A were 2009 and 2012, respectively. These findings suggested that the ΨUSA300 clone had spread among PLWHIVs in Tokyo in the early 2010s, with stepwise acquisition of lineage-specific nonsynonymous mutations.
Insights
The methicillin-resistant Staphylococcus aureus (MRSA) clone ΨUSA300, rare in Japan, has spread among people living with HIV in Tokyo since the early 2010s. This clone acquired specific mutations over time, indicating distinct evolutionary patterns.
Area of Science:
- Microbiology
- Genomics
- Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 is uncommon in Japan.
- A unique variant, ΨUSA300, and a USA300 outbreak have been reported in Tokyo, particularly among people living with HIV (PLWHIV).
Purpose of the Study:
- To investigate the evolutionary origins and genetic diversity of USA300-related MRSA clones circulating among PLWHIV in Tokyo.
- To compare the genetic features of these isolates with known USA300 genomes.
Main Methods:
- Whole-genome sequencing of MRSA isolates from PLWHIV in a Tokyo referral center.
- Comparative genomic analysis against established USA300 reference strains.
Main Results:
- 23 out of 28 MRSA isolates (82.1%) collected between 2016-2019 were identified as USA300.
- Of these, 22 isolates (95.6%) were the ΨUSA300 variant.
- ΨUSA300 showed identical genomic structure to reference USA300 but acquired 29 lineage-specific mutations, with divergence dates estimated at 2009 for ΨUSA300 and 2012 for a specific clade (Cluster A).
Conclusions:
- The ΨUSA300 MRSA clone has been spreading among PLWHIV in Tokyo since the early 2010s.
- This spread was associated with the stepwise acquisition of lineage-specific mutations, highlighting a unique evolutionary trajectory in this population.
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