Synopsis
Objectives Some single-centre studies have reported that MRSA carrying the staphylococcal cassette chromosome mec (SCCmec) type IV has been increasing in bloodstream infections (BSIs) in Japan. Therefore, we conducted nationwide surveillance for MRSA BSI to investigate the extent of such change across Japan.
Methods We recruited 51 Japanese hospitals from the Japanese Association for Infectious Diseases. MRSA isolates detected in two or more sets of blood cultures were collected between January and September 2019 and subjected to antimicrobial susceptibility testing. Whole-genome sequencing was also performed to determine SCCmec typing and multilocus typing and detect drug-resistance and virulence genes.
Results Two hundred seventy MRSA isolates were collected from 45 hospitals. The major combination types were ST8 with SCCmec type IV (ST8-IV) (30.7%), ST1-IV (29.6%), ST2725-IV (9.5%), ST764-II (8.1%), and ST5-II (7.8%). However, there were regional differences among the most major types. The most common types in western, eastern, and northern Japan were ST1-IV, ST8-IV, and ST5-II, respectively. ST8-IV, ST1-IV, and ST2725-IV exhibited greater susceptibility to clindamycin and minocycline than ST764-II and ST5-II, but erm(A) was detected in 93.8% and 100% of ST1-IV and ST2725-IV, respectively. Based on drug-resistance and virulence genes, characteristics of ST8-IV were different from those of ST1-IV and ST2725-IV. In addition, there were two major ST8-IV types with different characteristics.
Conclusions This study revealed that SCCmec type IV replaced SCCmec type II in MRSA BSI. In addition, SCCmec type IV was divided into several types with different characteristics.
Competing Interest Statement
The authors have declared no competing interest.
Funding Statement
This work was supported by the Japanese Association for Infectious Diseases, Grant for Clinical Research Promotion [the 1st (2018)]. Taiga Miyazaki, a member of the Committee for Clinical Research Promotion of the Japanese Association for Infectious Diseases, advised on study design, sample collection, and manuscript preparation. The funders had no role in the analysis or the decision to publish.
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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:
The Ethics Committee of Nagasaki University Hospital gave ethical approval for this work.
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Footnotes
Revise abstract and manuscript due to additional data.
Data Availability
The derived data supporting the findings of this study are presented in this paper. WGS data reported in this study are available in the DDBJ Sequence Read Archive (https://www.ddbj.nig.ac.jp/dra/index-e.html) under accession number DRA013058.