Serratia marcescens SCH909 is a multidrug resistant strain isolated in 1988 harboring three class 1 integrons. We wondered if these integrons were retained over time and if there were other antimicrobial resistant determinants contributing to its multidrug resistant profile. Genomic analysis showed a fourth multidrug resistance integron, a Tn7 transposon with dfrA1-sat2-ybeA-ybfA-ybfB-ybgA gene cassettes in the variable region. Insertion sequences were involved in the genesis of novel composite transposons in the L4 subtype plasmid pSCH909, such as Tn6824 carrying an arsenic regulon and two head to head class 1 integrons surrounded by two complete IS1. Remarkably, a novel chromosomal genomic island, SmaR, was identified, closely related to Multiple Antimicrobial Resistance Regions (MARR), usually found in AbaR0-type and AbGRI2-0 from global clones of Acinetobacter baumannii, and in M-type plasmids circulating in Enterobacteriaceae. Maintenance studies showed that the three class 1 integrons were maintained over 1 month without antimicrobial pressure. Since S. marcescens is considered a relevant nosocomial pathogen that can have a wide range of niches – human, plant, animal, soil and inanimate surfaces, our findings support the ability of this species to capture, maintain and spread a broad variety of antimicrobial resistance elements.

中文翻译：

---

粘质沙雷氏菌 SCH909 作为与抗菌素耐药机制广泛传播相关的遗传元件的储存库和来源

粘质沙雷氏菌SCH909 是一种多药耐药菌株，于 1988 年分离，含有三个 1 类整合子。我们想知道这些整合子是否会随着时间的推移而保留下来，是否还有其他抗菌素耐药性决定因素导致其多重耐药性特征。基因组分析显示了第四个多药耐药整合子，一个在可变区具有dfrA1-sat2-ybeA-ybfA-ybfB-ybgA基因盒的 Tn 7转座子。插入序列参与了 L4 亚型质粒 pSCH909 中新型复合转座子的发生，例如 Tn 6824携带一个砷调节子和两个被两个完整 IS 1包围的头对头 1 类整合子. 值得注意的是，发现了一个新的染色体基因组岛 SmaR，它与多重抗菌素耐药区 (MARR) 密切相关，通常在鲍曼不动杆菌全球克隆的 AbaR0 型和 AbGRI2-0 中以及在肠杆菌科中循环的 M 型质粒中发现. 维持研究表明，三个 1 类整合子在没有抗菌压力的情况下维持了 1 个月以上。由于S. marcescens被认为是一种相关的医院病原体，它可以具有广泛的生态位——人类、植物、动物、土壤和无生命的表面，我们的研究结果支持该物种捕获、维持和传播多种抗菌素耐药性的能力元素。