BACKGROUND Neonatal Staphylococcus aureus (S. aureus) bacteremia is an important cause of morbidity and mortality. In this study, we examined whether methicillin-susceptible S. aureus (MSSA) transmission and genetic makeup contribute to the occurrence of neonatal S. aureus bacteremia. METHODS A retrospective, single-centre study was performed. All patients were included who suffered from S. aureus bacteremia in the neonatal intensive care unit (NICU), Erasmus MC-Sophia, Rotterdam, the Netherlands, between January 2011 and November 2017. Whole-genome sequencing (WGS) was used to characterize the S. aureus isolates, as was also done in comparison to reference genomes. Transmission was considered likely in case of genetically indistinguishable S. aureus isolates. RESULTS Excluding coagulase-negative staphylococci (CoNS), S. aureus was the most common cause of neonatal bacteremia. Twelve percent (n = 112) of all 926 positive blood cultures from neonates grew S. aureus. Based on core genome multilocus sequence typing (cgMLST), 12 clusters of genetically indistinguishable MSSA isolates were found, containing 33 isolates in total (2-4 isolates per cluster). In seven of these clusters, at least two of the identified MSSA isolates were collected within a time period of one month. Six virulence genes were present in 98-100% of all MSSA isolates. In comparison to S. aureus reference genomes, toxin genes encoding staphylococcal enterotoxin A (sea) and toxic shock syndrome toxin 1 (tsst-1) were present more often in the genomes of bacteremia isolates. CONCLUSION Transmission of MSSA is a contributing factor to the occurrence of S. aureus bacteremia in neonates. Sea and tsst-1 might play a role in neonatal S. aureus bacteremia.

中文翻译：

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全基因组测序探索新生儿甲氧西林易感性金黄色葡萄球菌菌血症的医院传播和毒力。

背景技术新生儿金黄色葡萄球菌（S.aureus）菌血症是发病率和死亡率的重要原因。在这项研究中，我们检查了对甲氧西林敏感的金黄色葡萄球菌（MSSA）的传播和基因组成是否有助于新生儿金黄色葡萄球菌菌血症的发生。方法进行回顾性单中心研究。在2011年1月至2017年11月之间，包括荷兰鹿特丹伊拉斯姆斯·索菲亚新生儿重症监护病房（NICU）患有金黄色葡萄球菌菌血症的所有患者。使用全基因组测序（WGS）表征金黄色葡萄球菌分离株，与参考基因组相比也是如此。在遗传上无法区分的金黄色葡萄球菌分离株中，认为可能传播。结果不包括凝固酶阴性葡萄球菌（S. 金黄色葡萄球菌是新生儿菌血症的最常见原因。新生儿的全部926例阳性血液培养物中有12％（n = 112）种植了金黄色葡萄球菌。根据核心基因组多基因座序列分型（cgMLST），发现了12个遗传上无法区分的MSSA分离株簇，总共包含33个分离株（每簇2-4个分离株）。在其中的七个集群中，一个月内至少收集了两个已识别的MSSA分离株。在所有MSSA分离株的98-100％中存在六个毒力基因。与金黄色葡萄球菌参考基因组相比，在菌血症分离株的基因组中，编码葡萄球菌肠毒素A（海）和中毒性休克综合症毒素1（tsst-1）的毒素基因更为常见。结论MSSA的传播是导致新生儿金黄色葡萄球菌菌血症发生的一个因素。