Chew Ka Lip, Qiao Yuan, Lye Priscillia, Cruz Cabang Joey, Bakar Nur Aisyah Binte Abu, Tan Ker Xin, Teo Jeanette
Department of Laboratory Medicine, National University Hospital, Singapore.
Nanyang Link, School of Chemistry, Chemical Engineering and Biotechnology (CCEB), Nanyang Technological University, Singapore.
Emerg Microbes Infect. 2025 Dec;14(1):2539193. doi: 10.1080/22221751.2025.2539193. Epub 2025 Aug 6.
A 60-year-old male with recurrent bacteremia associated with necrotizing pancreatitis was followed over 17 months, during which six clinical isolates of were obtained. The index isolate (R1) was susceptible to aztreonam-avibactam (MIC 4 mg/L), but resistance (MIC >64 mg/L) emerged with isolate B1, collected one month later, and persisted in subsequent isolates. To investigate the genomic and phenotypic evolution of six clinical isolates, focusing on mechanisms underlying the emergence of aztreonam-avibactam resistance. Whole-genome sequencing was performed to determine species identity, phylogenetic relationships, and resistance determinants. Average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH) were used to confirm species classification. Comparative genomic analysis with R1 as a reference identified mutations associated with resistance. Structural modelling assessed the functional impact of key mutations. All isolates were sequence type ST44. Phylogenomic analysis revealed the isolates were more closely related to than , supported by ANI (97%) and DDH (76%). All isolates harboured , correlating with carbapenem resistance. Resistant isolates displayed a glycine insertion at position 420 in PBP3 (p.Gly420dup), which structural modelling indicated disrupted aztreonam-avibactam binding. A Gly151Asp substitution in OmpC was also identified, potentially affecting drug permeability. No mutations were observed in other porins (OmpA, OmpD, or OmpW). This study identifies a glycine insertion in PBP3 as a novel mechanism driving aztreonam-avibactam resistance in , supported by structural modelling and additional mutations in OmpC. This study provides evidence of a novel resistance mechanism to aztreonam-avibactam in , driven by a glycine insertion in PBP3 and supported by alterations in OmpC.
一名60岁男性，患有与坏死性胰腺炎相关的复发性菌血症，随访17个月，在此期间获得了6株临床分离菌株。首株分离菌（R1）对阿维巴坦复方制剂（MIC为4mg/L）敏感，但1个月后采集的B1分离菌出现耐药（MIC>64mg/L），且在后续分离菌中持续存在。为研究这6株临床分离菌的基因组和表型演变，重点关注阿维巴坦复方制剂耐药出现的机制。进行全基因组测序以确定菌种身份、系统发育关系和耐药决定因素。使用平均核苷酸同一性（ANI）和电子DNA-DNA杂交（DDH）来确认菌种分类。以R1为参考进行比较基因组分析，确定与耐药相关的突变。结构建模评估关键突变的功能影响。所有分离菌均为序列型ST44。系统发育基因组分析显示，这些分离菌与[具体菌种1]的亲缘关系比与[具体菌种2]更近，ANI（97%）和DDH（76%）支持这一结果。所有分离菌均携带[具体基因]，与碳青霉烯耐药相关。耐药分离菌在PBP3的420位插入了甘氨酸（p.Gly420dup），结构建模表明这破坏了阿维巴坦复方制剂的结合。还在OmpC中鉴定出Gly151Asp替换，可能影响药物通透性。在其他孔蛋白（OmpA、OmpD或OmpW）中未观察到突变。本研究确定PBP3中的甘氨酸插入是导致[具体菌种]对阿维巴坦复方制剂耐药的新机制，结构建模和OmpC中的其他突变提供了支持。本研究提供了证据，证明[具体菌种]中存在一种对阿维巴坦复方制剂的新耐药机制，由PBP3中的甘氨酸插入驱动，并得到OmpC改变的支持。
