Team Resist, UMR-1184 (INSERM - Université Paris-Saclay - CEA), LabEx Lermit, Faculty of Medicine, Le Kremlin-Bicêtre, France; EERA 'Evolution and Ecology of Resistance to Antibiotics' Unit, (Institut Pasteur - APHP - Université Paris Saclay), Le Kremlin-Bicêtre, France; Associated French National Reference Center for Antibiotic Resistance 'Carbapenemase-producing Enterobacteriaceae', Bacteriology-Hygiene Unit, APHP, Hôpital Bicêtre, Le Kremlin-Bicêtre, France.
Team Resist, UMR-1184 (INSERM - Université Paris-Saclay - CEA), LabEx Lermit, Faculty of Medicine, Le Kremlin-Bicêtre, France; Associated French National Reference Center for Antibiotic Resistance 'Carbapenemase-producing Enterobacteriaceae', Bacteriology-Hygiene Unit, APHP, Hôpital Bicêtre, Le Kremlin-Bicêtre, France.
Int J Antimicrob Agents. 2021 Mar;57(3):106285. doi: 10.1016/j.ijantimicag.2021.106285. Epub 2021 Jan 22.
Carbapenemase-producing Enterobacterales (CPE) is a major public-health concern. Here we describe the occurrence of bla in three isolates of Enterobacter hormaechei subsp. steigerwaltii. The bla gene was part of a class II transposon Tn1332 and was embedded in a remnant of a class 1 integron. Tn1332 was carried by a large, conjugative, non-typeable plasmid. The three isolates belonged to sequence type 90 (ST90). Two isolates (90H2 and 90H3) were highly related [<10 single nucleotide polymorphisms (SNPs)], whereas isolate 104D2 exhibited more than 50 SNPs and Tn1332 was inserted in a different place in the plasmid. Another IncHI-type plasmid carrying the extended-spectrum β-lactamase (ESBL) gene bla was identified in 90H2 and 90H3. Among the three isolates, isolate 104D2 was negative for detection of carbapenemase activity using the biochemical Carba NP test, despite the presence of Tn1332 on the same plasmid. Mutants of 104D2 with higher minimum inhibitory concentrations (MICs) for carbapenems were obtained and one mutant (m104D2) was analysed. In contrast to 104D2, mutant m104D2 gave a positive Carba NP test. The mutant possessed two copies of Tn1332 per cell and a nonsense mutation in WecA, an enzyme involved in enterobacterial common antigen and peptidoglycan intermediate biosynthesis. This study describes the first occurrence of Tn1332 in Enterobacterales and the phenotypic diversity of VIM-2-producing E. hormaechei.
产碳青霉烯酶肠杆菌科（CPE）是一个主要的公共卫生关注点。在这里，我们描述了 3 株霍氏肠杆菌亚种 steigerwaltii 中 bla 的发生情况。bla 基因是 II 类转座子 Tn1332 的一部分，嵌入在 1 类整合子的残余物中。Tn1332 由一个大型、可接合、不可分型的质粒携带。这三个分离株属于序列型 90（ST90）。两个分离株（90H2 和 90H3）高度相关[<10 个单核苷酸多态性（SNP）]，而分离株 104D2 则表现出超过 50 个 SNP，并且 Tn1332 插入在质粒的不同位置。另一个携带扩展谱β-内酰胺酶（ESBL）基因 bla 的 IncHI 型质粒在 90H2 和 90H3 中被鉴定。在这三个分离株中，尽管 104D2 上存在 Tn1332，但分离株 104D2 的 Carba NP 生化试验对碳青霉烯酶活性检测呈阴性。104D2 的突变体获得了更高的碳青霉烯最低抑菌浓度（MIC），并对其中一个突变体（m104D2）进行了分析。与 104D2 相比，突变体 m104D2 的 Carba NP 试验呈阳性。突变体每个细胞有两个 Tn1332 拷贝，并且在参与肠杆菌共同抗原和肽聚糖中间体生物合成的酶 WecA 中存在无意义突变。本研究描述了 Tn1332 在肠杆菌科中的首次出现以及产 VIM-2 的霍氏肠杆菌的表型多样性。
