Table_4_Whole-Genome Sequences of Five Acinetobacter baumannii Strains From a Child With Leukemia M2.xlsx

Acinetobacter baumannii is an opportunistic pathogen and is one of the primary etiological agents of healthcare-associated infections (HAIs). A. baumannii infections are difficult to treat due to the intrinsic and acquired antibiotic resistance of strains of this bacterium, which frequently limits therapeutic options. In this study, five A. baumannii strains (810CP, 433H, 434H, 483H, and A-2), all of which were isolated from a child with leukemia M2, were characterized through antibiotic susceptibility profiling, the detection of genes encoding carbapenem hydrolyzing oxacillinases, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), adherence and invasion assays toward the A549 cell line, and the whole-genome sequence (WGS). The five strains showed Multidrug resistant (MDR) profiles and amplification of the blaOXA-23 gene, belonging to ST758 and grouped into two PFGE clusters. WGS of 810CP revealed the presence of a circular chromosome and two small plasmids, pAba810CPa and pAba810CPb. Both plasmids carried genes encoding the Sp1TA system, although resistance genes were not identified. A gene-by-gene comparison analysis was performed among the A. baumannii strains isolated in this study and others A. baumannii ST758 strains (HIMFG and INCan), showing that 86% of genes were present in all analyzed strains. Interestingly, the 433H, 434H, and 483H strains varied by 8–10 single-nucleotide variants (SNVs), while the A2 and 810CP strains varied by 46 SNVs. Subsequently, an analysis using BacWGSTdb showed that all of our strains had the same resistance genes and were ST758. However, some variations were observed in relation to virulence genes, mainly in the 810CP strain. The genes involved in the synthesis of hepta-acylated lipooligosaccharides, the pgaABCD locus encoding poly-β-1-6-N-acetylglucosamine, the ompA gene, Csu pili, bap, the two-component system bfms/bfmR, a member of the phospholipase D family, and two iron-uptake systems were identified in our A. baumannii strains genome. The five A. baumannii strains isolated from the child were genetically different and showed important characteristics that promote survival in a hospital environment. The elucidation of their genomic sequences provides important information for understanding their epidemiology, antibiotic resistance, and putative virulence factors.

鲍曼不动杆菌（Acinetobacter baumannii）是一种机会致病菌，亦是医疗相关感染（healthcare-associated infections, HAIs）的主要致病原之一。该菌的菌株兼具固有与获得性抗生素耐药性，导致其感染治疗难度极大，常大幅限制临床治疗方案的选择。本研究针对5株分离自M2型白血病患儿的鲍曼不动杆菌菌株（810CP、433H、434H、483H及A-2），通过抗生素敏感性谱分析、碳青霉烯水解型苯唑西林酶编码基因检测、脉冲场凝胶电泳（pulsed-field gel electrophoresis, PFGE）、多位点序列分型（multilocus sequence typing, MLST）、针对A549细胞系的黏附与侵袭实验，以及全基因组测序（whole-genome sequence, WGS）完成了全面的菌株特征鉴定。5株菌株均呈现多重耐药（Multidrug resistant, MDR）表型，且均扩增出blaOXA-23基因，归属于ST758序列型，并被划分为2个PFGE簇。对810CP菌株的全基因组测序结果显示，其包含1条环状染色体与2个小型质粒pAba810CPa及pAba810CPb。两个质粒均携带Sp1TA系统编码基因，但未检测到耐药相关基因。本研究对本次分离得到的鲍曼不动杆菌菌株，与另外2株ST758型鲍曼不动杆菌菌株（HIMFG与INCan）开展了全基因逐位比较分析，结果显示所有分析菌株中共有86%的基因在所有菌株中均存在。值得注意的是，433H、434H与483H菌株之间仅存在8~10个单核苷酸变异（single-nucleotide variants, SNVs），而A-2与810CP菌株间的单核苷酸变异数目则达到46个。后续通过BacWGSTdb进行的分析显示，本研究的所有菌株均携带相同的耐药基因，且均为ST758型。但在毒力基因层面存在一定差异，其中以810CP菌株的差异最为显著。本研究的鲍曼不动杆菌菌株基因组中，共鉴定出与七酰化脂寡糖合成相关的基因、编码聚β-1,6-N-乙酰葡糖胺的pgaABCD基因座、外膜蛋白A（ompA）基因、Csu菌毛、bap基因、双组分系统bfms/bfmR、1个磷脂酶D家族成员编码基因，以及2个铁摄取系统相关基因。本次从该白血病患儿体内分离得到的5株鲍曼不动杆菌菌株在遗传学层面存在差异，且具备诸多可促进其在医院环境中存活的关键特性。对其基因组序列的解析，为阐明这些菌株的流行病学特征、抗生素耐药机制及潜在毒力因子提供了重要的研究依据。