Antimicrobial resistance is an increasingly serious problem in public health globally. Monitoring resistance levels within healthcare and community settings is critical to combat its ongoing increase. This study aimed to describe the rates and molecular mechanisms of mupirocin resistance in clinical Staphylococcus aureus isolates from Tygerberg Hospital, and to describe its association with strain types. We retrospectively selected 212 S. aureus isolates which were identified from blood samples and pus swabs during the years 2009–2011 and 2015–2017. The isolates were identified using conventional microbiological methods and genotyping was done using spa typing. Cefoxitin (30 μg) disc diffusion and the two disc strategy (5 μg and 200 μg) were used to determine susceptibility to methicillin and mupirocin, respectively. Isolates with high-level resistance were screened for the plasmid mediated genes mupA and mupB by PCR, and sequencing of the ileS gene was done for all isolates exhibiting low-level resistance to describe the mutations associated with this phenotype. Chi-square test was used to assess the associations between mupirocin resistance and S. aureus genotypes. Of 212 S. aureus isolates, 12% (n = 25) were resistant to mupirocin, and 44% (n = 93) were methicillin resistant. Strain typing identified 73 spa types with spa t045 being the most predominant constituting 11% of the isolates. High-level mupirocin resistance was observed in 2% (n = 5), and low-level resistance in 9% (n = 20) of the isolates. The prevalence of high-level mupirocin resistance amongst MRSA and MSSA was 4 and 1% respectively, while the prevalence of low-level mupirocin resistance was significantly higher in MRSA (18%) compared to MSSA (3%), (p = 0.032). mupA was the only resistance determinant for high-level resistance, and the IleS mutation V588F was identified in 95% of the isolates which showed low-level resistance. A significant association was observed between spa type t032 and high-level mupirocin resistance, and types t037 and t012 and low-level resistance (p < 0.0001). The study reported higher rates of low-level mupirocin resistance compared to high-level resistance, and in our setting, mupirocin resistance was driven by certain genotypes. Our study advocates for the continuous screening for mupirocin resistance in S. aureus in clinical settings to better guide treatment and prescribing practices.

中文翻译：

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来自南非开普敦一家医院的金黄色葡萄球菌分离株对莫匹罗星耐药的流行及其分子机制。

抗菌素耐药性是全球公共卫生中日益严重的问题。监测医疗保健和社区环境中的耐药水平对于抵抗其持续增长至关重要。本研究旨在描述泰格堡医院临床金黄色葡萄球菌分离株对莫匹罗星耐药的发生率和分子机制，并描述其与菌株类型的关系。我们回顾性选择了2009-2011年和2015-2017年从血液样本和脓拭子中鉴定出的212株金黄色葡萄球菌。使用常规微生物学方法鉴定分离物，并使用spa分型进行基因分型。头孢西丁（30μg）椎间盘扩散和两种椎间盘策略（5μg和200μg）分别用于确定对甲氧西林和莫匹罗星的敏感性。通过PCR筛选质粒介导的基因mupA和mupB的高抗性分离株，并对所有表现出低抗性的分离株进行ileS基因测序，以描述与此表型相关的突变。卡方检验用于评估莫匹罗星抗性和金黄色葡萄球菌基因型之间的关联。在212株金黄色葡萄球菌中，有12％（n = 25）对莫匹罗星有抗药性，有44％（n = 93）对甲氧西林有抗药性。菌株分型鉴定出73种水疗类型，其中水疗t045是最主要的，构成分离株的11％。分离株中有2％（n = 5）有高水平的莫匹罗星抗药性，有9％（n = 20）有低水平的莫比罗星抗药性。MRSA和MSSA中高水平的莫匹罗星耐药率分别为4％和1％，与MSA（3％）相比，MRSA（18％）的低水平莫匹罗星抗药性的患病率明显更高（p = 0.032）。mupA是唯一的高水平抗性决定因素，在95％表现出低水平抗性的分离物中鉴定出IleS突变V588F。在水疗类型t032和高水平的莫匹罗星抗药性之间以及t037和t012类型与低水平的抗药性之间观察到显着相关性（p <0.0001）。该研究报道，与高水平耐药相比，低水平的莫匹罗星耐药率更高，在我们的研究中，莫匹罗星的耐药性由某些基因型驱动。我们的研究主张在临床环境中连续筛查金黄色葡萄球菌对莫匹罗星的耐药性，以更好地指导治疗和开处方。（p = 0.032）。mupA是唯一的高水平抗性决定因素，在95％表现出低水平抗性的分离物中鉴定出IleS突变V588F。在水疗类型t032和高水平的莫匹罗星抗药性之间以及t037和t012类型与低水平的抗药性之间观察到显着相关性（p <0.0001）。该研究报道，与高水平耐药相比，低水平的莫匹罗星耐药率更高，在我们的研究中，莫匹罗星的耐药性由某些基因型驱动。我们的研究主张在临床环境中连续筛查金黄色葡萄球菌对莫匹罗星的耐药性，以更好地指导治疗和开处方。（p = 0.032）。mupA是唯一的高水平抗性决定因素，在95％表现出低水平抗性的分离物中鉴定出IleS突变V588F。在水疗类型t032和高水平的莫匹罗星抗药性之间以及t037和t012类型与低水平的抗药性之间观察到显着相关性（p <0.0001）。该研究报道，与高水平耐药相比，低水平的莫匹罗星耐药率更高，在我们的研究中，莫匹罗星的耐药性由某些基因型驱动。我们的研究主张在临床环境中连续筛查金黄色葡萄球菌对莫匹罗星的耐药性，以更好地指导治疗和开处方。在水疗类型t032和高水平的莫匹罗星抗药性之间以及t037和t012类型与低水平的抗药性之间观察到显着相关性（p <0.0001）。该研究报道，与高水平耐药相比，低水平的莫匹罗星耐药率更高，在我们的研究中，莫匹罗星的耐药性由某些基因型驱动。我们的研究主张在临床环境中连续筛查金黄色葡萄球菌对莫匹罗星的耐药性，以更好地指导治疗和开处方。在水疗类型t032和高水平的莫匹罗星抗药性之间以及t037和t012类型与低水平的抗药性之间观察到显着关联（p <0.0001）。该研究报道，与高水平耐药相比，低水平的莫匹罗星耐药率更高，在我们的研究中，莫匹罗星的耐药性由某些基因型驱动。我们的研究主张在临床环境中连续筛查金黄色葡萄球菌对莫匹罗星的耐药性，以更好地指导治疗和开处方。