Department of Microbiology, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India.
Faculty of Life and Allied Health Sciences, Ramaiah University of Applied Sciences, Bangalore, 560054, India.
Curr Microbiol. 2024 Oct 19;81(12):415. doi: 10.1007/s00284-024-03942-z.
Acinetobacter baumannii and Acinetobacter nosocomialis are the imperious pathogens in the intensive care units. We aimed to explore the genomic features of these pathogens to understand the factors influencing their plasticity. Using next-generation sequencing, two carbapenem-resistant A. baumannii (AbaBS-3, AbaETR-4) isolates and a pan-susceptible A. nosocomialis (AbaAS-5) isolate were characterised. All genomes exhibited 94% similarity with a degree of heterogeneity. AbaBS-3 and AbaETR-4 harboured antibiotic resistance gene (ARG) repertoire to most antibiotic classes. Carbapenem resistance was due to blaOXA-23 and blaOXA-66 besides the antibiotic efflux pumps. Diverse mobile genetic elements (MGE), insertion sequences (IS), prophages and virulence determinants with a plethora of stress response genes were identified in all three genomes. Class-1 integron in AbaETR-4, encoded genes that confer resistance to aminoglycosides, phenicol, sulfonamides and disinfectants. Substitutions in LpxACD and PmrCAB of AbaETR-4 confirmed the colistin resistance in vitro. Novel mutations in piuA, responsible for transporting cefiderocol, were found in AbaBS-3 and AbaETR-4. Plasmids carrying toxin-antitoxin systems, ARGs and ISs were present in these genomes. All three genomes harboured diverse protein secretion systems, virulence determinants related to immune evasion, adherence, biofilm formation and iron acquisition systems. AbaAS-5 exclusively harboured serine protease pkf, and CpaA substrate of type-II secretion system but lacked the acinetobactin-iron acquisition system. Our work delivers a holistic genome characterization of A. baumannii, coupled with a trailblazing attempt to study A. nosocomialis from India. The presence of ARGs and potential virulence factors interspersed with MGE is a cause for concern, depicting the dynamic adaptability mediated by genetic recombination.
鲍曼不动杆菌和医院不动杆菌是重症监护病房的主要病原体。我们旨在探索这些病原体的基因组特征，以了解影响其可塑性的因素。使用下一代测序，对两株耐碳青霉烯类的鲍曼不动杆菌（AbaBS-3、AbaETR-4）分离株和一株泛敏感的医院不动杆菌（AbaAS-5）分离株进行了特征描述。所有基因组与 94%的相似度，具有一定程度的异质性。AbaBS-3 和 AbaETR-4 携带了大多数抗生素类别的抗生素耐药基因（ARG）库。碳青霉烯类耐药是由于 blaOXA-23 和 blaOXA-66 以及抗生素外排泵所致。在所有三个基因组中都发现了不同的移动遗传元件（MGE）、插入序列（IS）、噬菌体和大量的毒力决定因素以及大量的应激反应基因。AbaETR-4 中的类-1 整合子，编码了对氨基糖苷类、青霉素、磺胺类和消毒剂耐药的基因。AbaETR-4 中 LpxACD 和 PmrCAB 的取代证实了其体外对粘菌素的耐药性。在 AbaBS-3 和 AbaETR-4 中发现了负责运输头孢地尔的 piuA 的新突变。这些基因组中存在携带毒素-抗毒素系统、ARGs 和 ISs 的质粒。所有三个基因组都携带有不同的蛋白分泌系统、与免疫逃避、粘附、生物膜形成和铁获取系统相关的毒力决定因素。AbaAS-5 仅携带丝氨酸蛋白酶 pkf 和 II 型分泌系统的 CpaA 底物，但缺乏乙酰丁胺酸-铁获取系统。我们的工作提供了对鲍曼不动杆菌的全面基因组特征描述，并开创性地尝试研究来自印度的医院不动杆菌。ARGs 和潜在毒力因子与 MGE 交织在一起，令人担忧，这表明了遗传重组介导的动态适应性。
