Department of Microbiology, University of Manitoba Winnipeg, Winnipeg, MB, R3T 2N2, Canada.
Programa de Genómica Evolutiva, Centro de Ciencias Génomicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.
Eur J Clin Microbiol Infect Dis. 2024 Oct;43(10):1939-1949. doi: 10.1007/s10096-024-04873-0. Epub 2024 Jul 29.
Non-baumannii Acinetobacter spp. are becoming more prevalent in clinical settings including those that present resistance to last-resort antibiotics such as colistin. AB222-IK40 is an Acinetobacter courvalinii strain isolated from the Ottawa Hospital Research Institute located in Ottawa, Canada. To our knowledge, it is the first report of clinical A. courvalinii in Canada. Based on the susceptibility profile, AB222-IK40 is resistant to colistin and non-susceptible to ertapenem. Whole-genome sequencing allowed for genomic investigation into colistin resistance mechanisms. No previously identified mechanism(s) were observed, but a mobile colistin resistance (mcr)-like gene and a UDP-glucose dehydrogenase gene were identified. Based on phylogenomic analyses, the mcr-like gene is an intrinsic phosphoethanolamine transferase. This gene family is implicated in one of the many mechanisms responsible for colistin resistance in Acinetobacter baumannii as well as Acinetobacter modestus. UDP-glucose dehydrogenase is involved in colistin resistance in Enterobacterales and has been shown to be involved in capsule formation in A. baumannii. Global lipidomics revealed greater abundance of phosphatidyl-myo-inositol and lyso-phosphatidyl ethanolamine moieties in the membrane of A. courvalinii than in A. baumannii. Lipidomic profiles showed differences that were probably responsible for the colistin resistance phenotype in AB222-IK40. This isolate was also hypervirulent based on survival assays in Galleria mellonella. As this is the first report of A. courvalinii from a hospital in Canada, this species may be an emerging clinical pathogen, and therefore, it is important to understand this mechanism of its colistin resistance and hypervirulence.
非鲍曼不动杆菌不动杆菌属在临床环境中越来越普遍，包括那些对最后一线抗生素（如黏菌素）具有耐药性的环境。AB222-IK40 是一种从加拿大渥太华医院研究所分离的courvalinii 型不动杆菌。据我们所知，这是加拿大首例临床 courvalinii 型不动杆菌的报告。根据药敏谱，AB222-IK40 对黏菌素耐药，对厄他培南不敏感。全基因组测序允许对粘菌素耐药机制进行基因组研究。未观察到先前确定的机制，但鉴定出了一个移动粘菌素耐药（mcr）样基因和一个 UDP-葡萄糖脱氢酶基因。基于系统发育基因组分析，mcr 样基因是一种内在的磷酸乙醇胺转移酶。该基因家族与许多导致鲍曼不动杆菌和 modestus 不动杆菌粘菌素耐药的机制有关。UDP-葡萄糖脱氢酶参与肠杆菌科的粘菌素耐药，并且已显示与鲍曼不动杆菌的荚膜形成有关。全局脂质组学研究表明，courvalinii 型不动杆菌的膜中磷脂酰肌醇和溶磷脂酰乙醇胺部分的丰度高于鲍曼不动杆菌。脂质组学分析显示出差异，这可能是 AB222-IK40 粘菌素耐药表型的原因。该分离株在金叶甲虫（Galleria mellonella）的生存试验中也具有高毒力。由于这是加拿大医院首次报告 courvalinii 型不动杆菌，因此该物种可能是一种新兴的临床病原体，因此了解其粘菌素耐药和高毒力的机制非常重要。
