Department of Laboratory Medicine, Foshan Fourth People's Hospital, Foshan, 528000, Guangdong, China.
Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Laboratory Medicine, Jinan, 250014, Shandong, China.
BMC Microbiol. 2021 Oct 18;21(1):281. doi: 10.1186/s12866-021-02344-6.
BACKGROUND: Bloodstream infection (BSI) caused by Staphylococcus aureus (S. aureus) can be life-threatening and pose a great challenge to infection control and clinical treatment. However, little information exists regarding the characterization of S. aureus in BSI patients in Shandong, China. To identify the clonality, virulence genes, and antibiotic resistance of S. aureus in blood, a total of 101 nonrepetitive blood isolates were collected. The antibiotic resistance phenotypes were determined, and virulence genes were analyzed with polymerase chain reaction (PCR). Finally, the genetic relatedness was investigated with Staphylococcus chromosomal cassette mec (SCCmec) typing for methicillin-resistant S. aureus (MRSA) isolates, Staphylococcal protein A (spa), and multilocus sequence typing (MLST) for all of 101 isolates. RESULTS: Of the 101 S. aureus isolates, 24 MRSA isolates and 77 methicillin-susceptible S. aureus (MSSA) isolates were identified. Overall, MRSA isolates had higher resistance rates than MSSA isolates when exposed to any of the 15 antibiotics tested in this study except for trimethoprim/sulfamethoxazole. Among the 17 virulence genes tested in this study, hla, hld, and hlg could be detected in all isolates. MRSA isolates were more likely to carry seb and hlb genes, while MSSA isolates were more likely to carry seg and sei genes. Thirty-five sequence types (STs) and 49 spa types were identified, of which ST59-t437 and ST398-t571 were the most abundant. These two genotypes were also the most abundant ST-spa types in MRSA and MSSA isolates, but their abundances shifted over time, with ST398-t571 being the predominant genotype from 2016 to 2017, and ST59-t437 from 2018 to 2020. Besides, all the ST59-t437 isolates harbored hlgb gene, whereas most (88.9%) ST398-t571 did not. In addition, twenty-four MRSA isolates were subject to SCCmec typing. SCCmec IVa was the most prevalent SCCmec type, and all the ST59-t437 MRSA isolates were SCCmec IVa. We also observed 15 new STs, and some of them were MRSA. CONCLUSION: These findings provide additional observations and epidemiological data for blood S. aureus isolates, which can improve future infection-control measures and aid in potential clinical treatments in hospitals and other clinical settings.
背景：金黄色葡萄球菌（S. aureus）引起的血流感染（BSI）可能危及生命，对感染控制和临床治疗构成巨大挑战。然而，关于中国山东地区 BSI 患者金黄色葡萄球菌的特征，目前信息有限。为了鉴定血液中金黄色葡萄球菌的克隆性、毒力基因和抗生素耐药性，共采集了 101 份非重复血样。采用聚合酶链反应（PCR）检测抗生素耐药表型和毒力基因。最后，对耐甲氧西林金黄色葡萄球菌（MRSA）分离株进行葡萄球菌染色体盒 mec（SCCmec）分型、所有 101 株分离株进行葡萄球菌蛋白 A（spa）和多位点序列分型（MLST），以分析遗传相关性。
结果：在 101 株金黄色葡萄球菌分离株中，鉴定出 24 株 MRSA 分离株和 77 株甲氧西林敏感金黄色葡萄球菌（MSSA）分离株。总体而言，MRSA 分离株对本研究中测试的 15 种抗生素中的任何一种的耐药率均高于 MSSA 分离株，除甲氧苄啶/磺胺甲噁唑外。在本研究中检测到的 17 种毒力基因中，hla、hld 和 hlg 可在所有分离株中检测到。MRSA 分离株更容易携带 seb 和 hlb 基因，而 MSSA 分离株更容易携带 seg 和 sei 基因。共鉴定出 35 种序列型（ST）和 49 种 spa 型，其中 ST59-t437 和 ST398-t571 最为丰富。这两种基因型也是 MRSA 和 MSSA 分离株中最丰富的 ST-spa 型，但它们的丰度随时间发生变化，ST398-t571 是 2016 年至 2017 年的主要基因型，而 ST59-t437 是 2018 年至 2020 年的主要基因型。此外，所有 ST59-t437 分离株均携带 hlgb 基因，而大多数（88.9%）ST398-t571 则没有。此外，对 24 株 MRSA 分离株进行 SCCmec 分型。SCCmec IVa 是最常见的 SCCmec 型，所有 ST59-t437 MRSA 分离株均为 SCCmec IVa。我们还观察到 15 种新的 ST，其中一些为 MRSA。
结论：这些发现为血液金黄色葡萄球菌分离株提供了更多的观察和流行病学数据，可改善未来的感染控制措施，并有助于医院和其他临床环境中的潜在临床治疗。
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