Whole Genome Sequence Analysis of Two Oxacillin-Resistant and mecA-Positive Strains of Staphylococcus haemolyticus Isolated from Ear Swab Samples of Patients with Otitis Media

Abstract

Objective

Staphylococcus haemolyticus can cause a series of infections including otitis media (OM), and the oxacillin-resistant S. haemolyticus has become a serious health concern. This study aimed to investigate the genomic characteristics of two strains of oxacillin-resistant and mecA-positive S. haemolyticus isolated from the samples of ear swabs from patients with OM and explore their acquired antibiotic resistance genes (ARGs) and the mobile genetic elements (MGEs).

Methods

Two oxacillin-resistant S. haemolyticus strains, isolated from ear swab samples of patients with OM, underwent antimicrobial susceptibility evaluation, followed by whole-genome sequencing. The acquired ARGs and the MGEs carried by the ARGs, harbored by the genomes of two strains of S. haemolyticus were identified.

Results

The two strains of oxacillin-resistant S. haemolyticus (strain SH1275 and strain SH9361) both carried the genetic contexts of mecA with high similarity with the SCCmec type V(5C2&5) subtype c. Surprisingly, the chromosomal aminoglycoside resistance gene aac(6’)-aph(2”) harbored by S. haemolyticus strain SH936 was flanked by two copies of IS256, forming the IS256-element (IS256-GNAT-[aac(6’)-aph(2”)]-IS256), which was widely present in strains of both Staphylococcus and Enterococcus genus. Furthermore, the two strains of oxacillin-resistant and MDR S. haemolyticus were found to harbor antimicrobial resistance plasmids, including one 26.9-kb plasmid (pSH1275-2) containing msr(A)–mph(C)) and qacA, one mobilizable plasmid pSH1275-3 harboring vga(A)_LC, one plasmid (pSH9361-1) carrying erm(C), and one plasmid (pSH9361-2) carrying qacJ.

Conclusion

The systematic analysis of whole-genome sequences provided insights into the mobile genetic elements responsible for multi-drug resistance in these two strains of oxacillin-resistant and mecA-positive S. haemolyticus, which will assist clinicians in devising precise, personalized, and clinical therapeutic strategies for treating otitis media caused by multi-drug resistant S. haemolyticus.

Keywords:

• Staphylococcus haemolyticus
• ear swabs
• mecA
• antimicrobial resistance plasmid
• whole genome sequence

Ethical Approval Statement

This study has been approved by the Ethics Committee of Zhuhai People’s Hospital. The present study was a study focusing on bacteria and did not contain any sensitive personal information. Therefore, informed consent was not required according to “Measures for the Ethical Review of Biomedical Research Involving Humans” (https://www.gov.cn/gongbao/content/2017/content_5227817.htm).

Disclosure

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

This work was supported financially by the grants from the Science and Technology Projects of Social Development in Zhuhai (Grant No. ZH22036201210111PWC), and the Xiangshan Talent Project of Zhuhai People’s Hospital (Grant No. 2020XSYC-02).