UNASSIGNED: Species confirmation of L2724hy was achieved through 16S rRNA sequencing and Average Nucleotide Identity (ANI) analysis. Antimicrobial susceptibility testing (AST) employed the agar dilution and micro broth dilution methods. Identification of resistance genes was carried out by PCR and whole-genome sequencing (WGS). Essential resistance gene locations were verified by S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and southern hybridization experiments. Subsequent WGS data analysis delved into drug resistance genes and plasmids.
UNASSIGNED: The confirmation of the strain L2724hy as an extensive drug-resistant Citrobacter portucalensis, resistant to almost all antibiotics tested except polymyxin B and tigecycline, was achieved through 16S rRNA sequencing, ANI analysis and AST results. WGS and subsequent analysis revealed L2724hy carrying bla SFO-1, bla NDM-1, and bla KPC-2 on plasmids of various sizes. The uncommon ESBL gene bla SFO-1 coexists with the fosA3 gene on an IncFII plasmid, featuring the genetic environment IS26-fosA3-IS26-ampR-bla SFO-1-IS26. The bla NDM-1 was found on an IncX3 plasmid, coexisting with bla SHV-12, displaying the sequence IS5-IS3000-IS3000-Tn2-bla NDM-1-ble-trpF-dsbD-cutA-gros-groL, lacking ISAa125. The bla KPC-2 is located on an unclassified plasmid, exhibiting the sequence Tn2-tnpR-ISKpn27-bla KPC-2-ISKpn6-korC. Conjugation assays confirmed the transferability of both bla NDM-1 and bla KPC-2.
UNASSIGNED: We discovered the coexistence of bla SFO-1, bla NDM-1, and bla KPC-2 in C. portucalensis for the first time, delving into plasmid characteristics and transfer mechanisms. Our finding highlights the importance of vigilant monitoring of drug-resistance genes and insertion elements in uncommon strains.
■通过16SrRNA测序和平均核苷酸同一性(ANI)分析实现了L2724hy的物种确认。抗微生物药敏试验(AST)采用琼脂稀释和微量肉汤稀释方法。通过PCR和全基因组测序(WGS)进行抗性基因的鉴定。通过S1核酸酶脉冲场凝胶电泳(S1-PFGE)和Southern杂交实验验证了基本抗性基因位置。随后的WGS数据分析深入研究了耐药基因和质粒。
■确认L2724hy菌株是一种广泛的耐药性柠檬酸杆菌,除了多粘菌素B和替加环素外,几乎所有测试的抗生素都具有耐药性,是通过16SrRNA测序实现的,ANI分析和AST结果。WGS和随后的分析显示,L2724hy在各种大小的质粒上携带blaSFO-1,blaNDM-1和blaKPC-2。不常见的ESBL基因blaSFO-1与IncFII质粒上的fosA3基因共存,具有遗传环境IS26-fosA3-IS26-ampR-blaSFO-1-IS26。在IncX3质粒上发现了blaNDM-1,与blaSHV-12共存,显示序列IS5-IS3000-IS3000-Tn2-blaNDM-1-ble-trpF-dsbD-cutA-gros-groL,缺少ISAa125。blaKPC-2位于未分类的质粒上,显示序列Tn2-tnpR-ISKpn27-blaKPC-2-ISKpn6-korC。缀合测定证实了blaNDM-1和blaKPC-2两者的可转移性。
■我们首次发现了在C.portucalensis中blaSFO-1,blaNDM-1和blaKPC-2的共存,深入研究质粒特性和转移机制。我们的发现强调了警惕监测罕见菌株中耐药基因和插入元件的重要性。