Yan Lixin, Ma Tingting, Wang Wen, Cai Zhen, Du Hong, Chen Zhongju, Han Renru, Guo Yan, Li Gang, Jia Wei, Tao Jia
The First Clinical Medical College of Ningxia Medical University, Yinchuan, China.
Laboratory Medical Center, General Hospital of Ningxia Medical University, Yinchuan, China.
Front Microbiol. 2025 May 7;16:1582851. doi: 10.3389/fmicb.2025.1582851. eCollection 2025.
To elucidate the molecular epidemiology of tigecycline and carbapenem-resistant isolates and mechanisms of tigecycline resistance.
We gathered 31 unduplicated strains of tigecycline-resistant from six hospitals nationwide. Antimicrobial susceptibility testing, phenotypic detection, and PCR identification were performed first, followed by homology analysis using MLST and PFGE. Conjugation transfer experiments using resistance gene plasmids were carried out, and the conjugates' growth curves were examined. All strains were sequenced using the Illumina HiSeq technology, and we identified a strain KP28 carrying a complete gene cluster . Then, its plasmid was further constructed using the PacBio platforms to complete the frame. The genetic connection of the gene cluster carried by KP28 was established using core genome analyses.
All 31 tigecycline-resistant strains (TG-CRE) were multidrug resistant. PFGE classified strains of CRKP, CRECL, and CRKAE into 16 distinct spectra, 6 distinct spectra, and 3 distinct spectra. MLST results showed a high concentration of ST11 in CRKP strains and a predominance of ST116 in CRECL strains, suggesting possible clonal transmission or selective dominance. The findings of the plasmid conjugation assay revealed that three strains expressing carbapenem resistance genes were effectively transmitted to the recipient cell EC600. WGS data revealed that these 31 strains include 79 resistance genes, with one strain (KP28) carrying the whole tigecycline resistance gene cluster, . This resistance gene is contained in a large IncHI5 plasmid, which is difficult to transfer.
The overall carriage rate of the gene cluster was found to be low among the five Chinese hospitals investigated. Conversely, (A) mutations were present in most of the strains. Bacteria with the carbapenem resistance genes and are vulnerable to horizontal transmission. Increasing the risk of transmission of antibiotic-resistant genes.
阐明替加环素和碳青霉烯类耐药菌株的分子流行病学以及替加环素耐药机制。
我们从全国六家医院收集了31株非重复的替加环素耐药菌株。首先进行药敏试验、表型检测和PCR鉴定，随后使用多位点序列分型（MLST）和脉冲场凝胶电泳（PFGE）进行同源性分析。使用耐药基因质粒进行接合转移实验，并检测接合子的生长曲线。所有菌株均采用Illumina HiSeq技术进行测序，我们鉴定出一株携带完整基因簇的菌株KP28。然后，使用PacBio平台进一步构建其质粒以完成框架。使用核心基因组分析确定KP28携带的基因簇的遗传联系。
所有31株替加环素耐药菌株（TG-CRE）均为多重耐药。PFGE将耐碳青霉烯肺炎克雷伯菌（CRKP）、耐碳青霉烯阴沟肠杆菌（CRECL）和耐碳青霉烯产气肠杆菌（CRKAE）菌株分别分为16个不同谱型、6个不同谱型和3个不同谱型。MLST结果显示CRKP菌株中ST11的浓度较高，CRECL菌株中ST116占优势，提示可能存在克隆传播或选择性优势。质粒接合试验结果表明，三株表达碳青霉烯耐药基因的菌株有效地转移到了受体细胞EC600。全基因组测序（WGS）数据显示，这31株菌株包含79个耐药基因，其中一株（KP28）携带完整的替加环素耐药基因簇。该耐药基因包含在一个大型IncHI5质粒中，难以转移。
在所调查的五家中国医院中，该基因簇的总体携带率较低。相反，大多数菌株中存在（A）突变。携带碳青霉烯耐药基因 和 的细菌易发生水平传播。增加了抗生素耐药基因传播的风险。
