Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Clinical Laboratory Sciences and Medical Biotechnology College of Medicine, National Taiwan University, Taipei, Taiwan.
Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan; College of Medicine, Yang-Ming University, Taipei, Taiwan.
Int J Antimicrob Agents. 2018 Jul;52(1):70-75. doi: 10.1016/j.ijantimicag.2018.02.014. Epub 2018 Mar 2.
Clinical data related to bacteraemia caused by mecA-positive borderline oxacillin-resistant Staphylococcus aureus (BORSA) isolates [minimum inhibitory concentrations (MICs) of 0.5-4 mg/L] are limited. Patients aged ≥15 years with bacteraemia due to BORSA who were admitted to the emergency department of a Taiwanese tertiary hospital between January 2001 and December 2015 were evaluated. Clinical characteristics of patients with bacteraemia caused by BORSA, methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) were compared. MICs of 12 antibiotics were determined by agar dilution. Genetic characteristics of 64 available BORSA isolates were analysed by detection of the SCCmec gene, the mecA promoter region sequence and multilocus sequence typing (MLST). Pulsed-field gel electrophoresis (PFGE) was performed to identify the clonality of the emerging ST isolates. The quinolone resistance genes were analysed for the emerging ciprofloxacin-resistant ST45 clone isolates. Among the 65 BORSA bacteraemic patients, in-hospital mortality was 24.6%, significantly lower than that of MRSA patients (38.5%) (P = 0.03). Underlying conditions were similar between BORSA and MRSA patients, but with less dialysis in the former (P = 0.01). Multivariate analysis revealed that septic shock [odds ratio (OR) = 15.95] and bacteraemia originating from lower respiratory tract infection (OR = 5.78) were two independent risk factors for 30-day mortality. The ST45 clone with high-level ciprofloxacin resistance (MICs of 8-128 mg/L) replaced ST59 as the predominant clone since 2012, although no major clustering was detected. In conclusion, the emerging multidrug-resistant ST45 clone has replaced ST59 as the most common among BORSA isolates.
临床数据与耐苯唑西林边缘型金黄色葡萄球菌（BORSA）引起的菌血症（最低抑菌浓度（MIC）为 0.5-4mg/L）相关有限。评估了 2001 年 1 月至 2015 年 12 月期间，台湾一家三级医院急诊部门因 BORSA 菌血症入院的年龄≥15 岁患者。比较了 BORSA 菌血症、耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）患者的临床特征。采用琼脂稀释法测定 12 种抗生素的 MIC。通过检测 SCCmec 基因、mecA 启动子区序列和多位点序列分型（MLST）分析 64 株可利用的 BORSA 分离株的遗传特征。采用脉冲场凝胶电泳（PFGE）对新出现的 ST 分离株进行克隆性分析。对新出现的环丙沙星耐药 ST45 克隆分离株的喹诺酮耐药基因进行分析。在 65 例 BORSA 菌血症患者中，院内死亡率为 24.6%，明显低于 MRSA 患者（38.5%）（P=0.03）。BORSA 和 MRSA 患者的基础疾病相似，但前者透析较少（P=0.01）。多变量分析显示，败血症休克（OR=15.95）和下呼吸道感染引起的菌血症（OR=5.78）是 30 天死亡率的两个独立危险因素。自 2012 年以来，高耐环丙沙星的 ST45 克隆（MIC 值为 8-128mg/L）取代 ST59 成为主要克隆，尽管未检测到主要聚类。总之，新兴的多药耐药 ST45 克隆已取代 ST59 成为 BORSA 分离株中最常见的克隆。
