Molecular Epidemiology of Community-Acquired Methicillin-Resistant Staphylococcus aureus and Clinical Characteristics of Different Sites of Infection

Abstract

Purpose

Since community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized, the molecular epidemiology of CA-MRSA in China has been diverse. It is unclear whether different sites of CA-MRSA infection differ in antimicrobial resistance and clinical characteristics. The purpose of this study was to identify the molecular types, virulence factors and antimicrobial resistance of CA-MRSA strains and to analyze the clinical characteristics of different sites of CA-MRSA infection.

Methods

26 CA-MRSA strains were screened from Beijing Chao-Yang Hospital from 2014 to 2022. SCCmec type, MLST type, spa type, Panton–Valentine leukocidin (PVL), hemolysin α (Hla), phenolic soluble regulatory protein α (PSMα), toxic shock syndrome toxin-1 (TSST-1), and enterotoxin (SE) A to E were detected by PCR and gene sequencing. Antimicrobial susceptibility tests and the clinical features of CA-MRSA infection cases were collected for statistical analysis.

Results

The predominant type of CA-MRSA was ST59-t437-IV. New non-epidemic types, SCCmec VII, were also found. PVL was seen in 65.4% of CA-MRSA strains and TSST-1 was only be detected in 3.8% of CA-MRSA strain which caused poor prognosis. There were three types of infections: pneumonia (61.5%), infective endocarditis (7.7%), and skin and soft tissue infections (SSTIs) (30.8%). CA-MRSA pneumonia cases were secondary to influenza infection (37.5%). Patients with CA-MRSA-associated infective endocarditis were more likely to have underlying cardiac diseases. Patients with CA-MRSA-associated SSTIs were more likely to have a history of diabetes mellitus, and strains in this group were more susceptible to erythromycin and clindamycin.

Conclusion

ST59-t437-IV was the primary CA-MRSA type in our research and in China. We proposed that TSST-1 might be one of the indicators to predict the severity and prognosis of CA-MRSA infection. Different sites of CA-MRSA infection had difference in antibiotics susceptibility testing and underlying diseases of patients. It could provide a new perspective on treating different types of CA-MRSA infection.

Keywords:

• community, acquired methicillin, resistant Staphylococcus aureus
• staphylococcal chromosomal cassette mec type
• Panton-Valentine leukocidin
• antibiotic resistance
• pneumonia

Ethical Standards

The Beijing Chao-Yang Hospital Ethics Committee (2015-KE-158) approved the study and written informed consent was obtained from every participant. All participants have been informed of the use of their samples and clinical tests results and have given their informed consent. The authors assert that all procedures contributing to this work comply with the ethical standards of relevant national and institutional committees on human experimentation and with Helsinki Declaration of 1975, revised in 2013.

Acknowledgments

We thank all those who have contributed S. aureus genome sequences to GenBank (https://www.ncbi.nlm.nih.gov/genbank), the MLST database (https://pubmlst.org/), and the spa database (https://cge.food.dtu.dk/services/spaTyper/). The authors would like to thank all Department of Infectious Diseases and Clinical Microbiology staff members at Beijing Chao-Yang Hospital (Beijing, China) for contributing to this work. We thank LetPub for its linguistic assistance during the preparation of this manuscript.

Author Contributions

All authors made a significant contribution to the work reported, whether that is 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 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 Reform and Development Program of Beijing Institute of Respiratory Medicine. The funder played no role in the design of the study, nor in the collection, analysis, and interpretation of data, nor in writing the manuscript.