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ORIGINAL RESEARCH

Comparison of Molecular Characteristics Between Methicillin-Resistant and -Susceptible Staphylococcus aureus Clinical Isolates by Whole-Genome Sequencing

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Pages 2949-2958 | Published online: 09 Jun 2022
 

Abstract

Introduction

The transmission of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) are great public health concern worldwide. To better understand S. aureus evolution and dissemination, we compared the molecular features of MSSA and MRSA isolates.

Methods

In this study, 74 MSSA and 102 MRSA non-duplicate isolates were recovered from clinical samples between 2016 and 2020. Molecular epidemiology, antimicrobial resistance determinants, and virulence gene profiles were carried out by whole-genome sequencing (WGS).

Results

Twenty distinct sequence types were identified in MRSA isolates, with the most common being ST59, ST630, and ST338. The major genotypes of MSSA were ST188 and ST7. The toxin genes clfA, sek, and seq were significantly associated with MRSA, while splA/B, clfB, map, sdrC/D, and sem-sen-seo-seu were detected more frequently in MSSA isolates than MRSA (P < 0.05). The tst positive isolates were more commonly identified in CC1 and CC72, whereas lukE/D was mainly found in the CC7, CC15, CC88, and completely absent in CC59 clones.

Conclusion

Our results compared the genetic diversity between MRSA and MSSA strains, suggesting efforts to fight infections caused by MSSA need to be intensified due to MSSA isolates carrying wide range of virulence factors. Comparative epidemiological studies of large populations of MSSA and MRSA will be necessary in the future to understand how MSSA and MRSA populations may co-evolve and interact in the future.

Abbreviations

MRSA, Methicillin-resistant S. aureus; SCCmec, Staphylococcal cassette chromosome mec; MSSA, methicillin-susceptible S. aureus; WGS, whole-genome sequencing; MLST, multilocus sequence typing; STs, sequence types; CCs, clonal complexes.

Ethics Statement

As the Staphylococcus aureus clinical isolation in this study was part of the routine hospital laboratory procedure, we have confirmed that the isolate has no identifiable patient data, the Second Affiliated Hospital of Nanchang University Medical Research Ethics Committee exempted this research for review.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis, and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by the Jiangxi Natural Science Foundation (No. 20181BAB205066), the Jiangxi Natural Science Foundation (No. 20202BABL216039), the Jiangxi Natural Science Foundation (20202BAB216021).