摘要
      溶血性葡萄球菌是新生儿晚发性败血症的主要原因，地方性克隆通常具有多重耐药性。这种细菌还可以作为更多致病细菌的基因库。分子流行病学在了解细菌致病性和预防感染方面具有重要意义。描述40多年来从瑞典新生儿重症监护室（NICU）新生儿血液培养物中分离的溶血性链球菌的分子流行病学，包括抗生素耐药性基因（ARGs）、毒力因子，以及与国际分离株的比较。对分离物进行全基因组测序，并使用核心基因组中的单核苷酸多态性来绘制相关性。研究了先前描述的ARGs和毒力基因的发生情况。椎间盘扩散和梯度试验用于确定表型抗性。结果显示，20世纪90年代，溶血性链球菌在该新生儿重症监护室爆发了克隆性疫情。所有分离株中有28株（82%）存在多药耐药性，27株（79%）同时出现氨基糖苷类和甲氧西林耐药性。没有分离株对万古霉素产生耐药性。编码ARGs和毒力因子的基因频繁出现。此次爆发的分离株在基因型和表型模式上更为同质。基因型和表型抗性组合是一致的。先前描述的溶血性链球菌的致病特征在目前的分离株中频繁出现，可能是由于医院选择压力导致流行病学成功。这项研究揭示的克隆爆发强调了遵守卫生程序的重要性，以防止未来的地方病爆发。
ABSTRACT
Staphylococcus haemolyticus is a major cause of late-onset sepsis in neonates, and endemic clones are often multidrug-resistant. The bacteria can also act as a genetic reservoir for more pathogenic bacteria. Molecular epidemiology is important in understanding bacterial pathogenicity and preventing infection. To describe the molecular epidemiology of S. haemolyticus isolated from neonatal blood cultures at a Swedish neonatal intensive care unit (NICU) over 4 decades, including antibiotic resistance genes (ARGs), virulence factors, and comparison to international isolates. Isolates were whole-genome sequenced, and single nucleotide polymorphisms in the core genome were used to map the relatedness. The occurrence of previously described ARGs and virulence genes were investigated. Disc diffusion and gradient tests were used to determine phenotypic resistance. The results revealed a clonal outbreak of S. haemolyticus at this NICU during the 1990s. Multidrug resistance was present in 28 (82%) of all isolates and concomitant resistance to aminoglycoside and methicillin occurred in 27 (79%). No isolates were vancomycin resistant. Genes encoding ARGs and virulence factors occurred frequently. The isolates in the outbreak were more homogenous in their genotypic and phenotypic patterns. Genotypic and phenotypic resistance combinations were consistent. Pathogenic traits previously described in S. haemolyticus occurred frequently in the present isolates, perhaps due to the hospital selection pressure resulting in epidemiological success. The clonal outbreak revealed by this study emphasizes the importance of adhering to hygiene procedures in order to prevent future endemic outbreaks.

https://journals.asm.org/doi/full/10.1128/spectrum.02452-22