Department of Microbiology, Juntendo University School of Medicine, Tokyo, Japan.
Department of Chemistry and Biotechnology, Kagoshima University, Kagoshima, Japan.
J Glob Antimicrob Resist. 2023 Jun;33:101-108. doi: 10.1016/j.jgar.2023.02.023. Epub 2023 Mar 9.
Colistin-resistant Gram-negative pathogens have become a serious worldwide medical problem. This study was designed to reveal the effects of an intrinsic phosphoethanolamine transferase from Acinetobacter modestus on Enterobacterales.
A strain of colistin-resistant A. modestus was isolated from a sample of nasal secretions taken in 2019 from a hospitalised pet cat in Japan. The whole genome was sequenced by next generation sequencing, and transformants of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae harbouring the phosphoethanolamine transferase-encoding gene from A. modestus were constructed. Lipid A modification in E. coli transformants was analysed using electrospray ionization mass spectrometry.
Sequencing of the entire genome revealed that the isolate harboured a phosphoethanolamine transferase-encoding gene, eptA_AM, on its chromosome. Transformants of E. coli, K. pneumoniae, and E. cloacae harbouring both the promoter and eptA_AM gene from A. modestus had 32-fold, 8-fold, and 4-fold higher minimum inhibitory concentrations (MICs) for colistin, respectively, than transformants harbouring a control vector. The genetic environment surrounding eptA_AM in A. modestus was similar to that surrounding eptA_AM in Acinetobacter junii and Acinetobacter venetianus. Electrospray ionization mass spectrometry analysis revealed that EptA_AM modified lipid A in Enterobacterales.
This is the first report to describe the isolation of an A. modestus strain in Japan and show that its intrinsic phosphoethanolamine transferase, EptA_AM, contributes to colistin resistance in Enterobacterales and A. modestus.
耐黏菌素革兰氏阴性病原体已成为全球严重的医学问题。本研究旨在揭示来自鲍曼不动杆菌的内在磷酸乙醇胺转移酶对肠杆菌科的影响。
从日本一家医院住院宠物猫的鼻部分泌物样本中分离出一株耐黏菌素的鲍曼不动杆菌。通过下一代测序对全基因组进行测序，并构建了携带鲍曼不动杆菌磷酸乙醇胺转移酶编码基因的大肠杆菌、肺炎克雷伯菌和阴沟肠杆菌转化体。使用电喷雾电离质谱分析大肠杆菌转化体的脂质 A 修饰。
全基因组测序显示，该分离株在其染色体上携带一个磷酸乙醇胺转移酶编码基因 eptA_AM。携带鲍曼不动杆菌启动子和 eptA_AM 基因的大肠杆菌、肺炎克雷伯菌和阴沟肠杆菌转化体的最低抑菌浓度（MIC）分别比携带对照载体的转化体高 32 倍、8 倍和 4 倍。鲍曼不动杆菌中 eptA_AM 周围的遗传环境与不动杆菌 junii 和 Acinetobacter venetianus 中 eptA_AM 周围的遗传环境相似。电喷雾电离质谱分析显示 EptA_AM 修饰了肠杆菌科的脂质 A。
这是首次报道在日本分离出一株鲍曼不动杆菌，并表明其内在的磷酸乙醇胺转移酶 EptA_AM 有助于肠杆菌科和鲍曼不动杆菌对黏菌素的耐药性。
