Introduction. Staphylococcus aureus is a major cause of hospital infections worldwide. Awareness towards methicillin-resistant S. aureus (MRSA) infections is high but attention towards borderline oxacillin-resistant S. aureus (BORSA) is limited, possibly due to an underestimated clinical relevance, presumption of low incidence and diagnostic limitations. Gap statement. BORSA surveillance has not been routinely implemented, and thus consensus with regard to a definition and infection control measures is lacking. Aim. Our goals were to investigate the occurrence, molecular characteristics and clinical manifestations of BORSA infections in the hospital setting. Methodology. Following an increased incidence in 2016, BORSA cases in 2014/2016 (in our institution) were more specifically evaluated. Medical records were reviewed to investigate epidemiological links, clinical characteristics and outcomes. Resistance and virulence markers were assessed by whole genome sequencing (WGS). Conventional methods: amplified fragment length polymorphism (AFLP) ; multilocus sequence typing (MLST) and multiple locus variable-number tandem repeat analysis (MLVA) were compared with core genome MLST (cgMLST) and whole-genome single nucleotide polymorphism (wgSNP) analysis to confirm genetic clusters. Results. From 2009 to 2013, BORSA comprised 0.1 % of all clinical S. aureus strains. In 2016, the incidence was six-fold higher in comparison to the baseline. Whole-genome SNP and cgMLST confirmed two BORSA clusters among patients with dermatological conditions. Patients with BORSA presented with skin infections, and one case developed a severe invasive infection with a fatal outcome. Infection control measures successfully prevented further transmission in both clusters. WGS findings showed that BORSA strains carried multiple resistance and virulence genes with increased pathogenic potential. Conclusion. WGS and cgMLST effectively characterized and confirmed BORSA clusters among at-risk patients with clinical manifestations ranging from mild skin infections to life-threatening bacteraemia. Clinical awareness and active monitoring are therefore warranted for the timely implementation of infection control measures to prevent BORSA transmission in high-risk patients.

中文翻译：

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全基因组测序评估临界耐苯唑西林金黄色葡萄球菌的医院传播

介绍。 金黄色葡萄球菌是全世界医院感染的主要原因。对耐甲氧西林金黄色葡萄球菌(MRSA) 感染的认识很高，但对临界耐苯唑西林金黄色葡萄球菌(BORSA) 的关注有限，这可能是由于低估了临床相关性、低发病率的假设和诊断限制。间隙声明。BORSA 监测尚未常规实施，因此在定义和感染控制措施方面缺乏共识。目的。我们的目标是调查医院环境中 BORSA 感染的发生、分子特征和临床表现。方法。 继 2016 年发病率增加后，更具体地评估了 2014/2016 年（在我们机构中）的 BORSA 病例。审查医疗记录以调查流行病学联系、临床特征和结果。通过全基因组测序（WGS）评估抗性和毒力标记。常规方法：扩增片段长度多态性（AFLP）；将多基因座序列分型 (MLST) 和多基因座可变数量串联重复分析 (MLVA) 与核心基因组 MLST (cgMLST) 和全基因组单核苷酸多态性 (wgSNP) 分析进行比较，以确认遗传簇。结果。从 2009 年到 2013 年，BORSA 占所有临床金黄色葡萄球菌的0.1% 菌株。2016 年，与基线相比，发病率高出六倍。全基因组 SNP 和 cgMLST 证实了皮肤病患者中有两个 BORSA 簇。BORSA 患者出现皮肤感染，1 例出现严重的侵袭性感染并导致死亡。感染控制措施成功阻止了两个集群的进一步传播。WGS 研究结果表明，BORSA 菌株携带多个具有增加致病潜力的抗性和毒力基因。结论。WGS 和 cgMLST 有效地表征并确认了临床表现从轻度皮肤感染到危及生命的菌血症的高危患者中的 BORSA 集群。因此，临床意识和积极监测是及时实施感染控制措施以防止高危患者中 BORSA 传播的必要条件。