Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China.
Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture of China, Yangzhou University, Yangzhou, China.
Front Cell Infect Microbiol. 2024 Jun 28;14:1399732. doi: 10.3389/fcimb.2024.1399732. eCollection 2024.
Tigecycline serves as a last-resort antimicrobial agent against severe infections caused by multidrug-resistant bacteria. Tet(X) and its numerous variants encoding flavin-dependent monooxygenase can confer resistance to tigecycline, with (X4) being the most prevalent variant. This study aims to investigate the prevalence and characterize tigecycline resistance gene (X) in isolates from various origins in Yangzhou, China, to provide insights into (X) dissemination in this region. In 2022, we tested the presence of (X) in 618 isolates collected from diverse sources, including patients, pig-related samples, chicken-related samples, and vegetables in Yangzhou, China. The antimicrobial susceptibility of (X)-positive isolates was conducted using the agar dilution method or the broth microdilution method. Whole genome sequencing was performed on (X)-positive strains using Illumina and Oxford Nanopore platforms. Four isolates from pig or pork samples carried (X4) and exhibited resistance to multiple antimicrobial agents, including tigecycline. They were classified as ST542, ST10, ST761, and ST48, respectively. The (X4) gene was located on IncFIA8-IncHI1/ST17 (n=2), IncFIA18-IncFIB(K)-IncX1 (n=1), and IncX1 (n=1) plasmids, respectively. These (X4)-carrying plasmids exhibited high similarity to other (X4)-bearing plasmids with the same incompatible types found in diverse sources in China. They shared related genetic environments of (X4) associated with IS, as observed in the first identified (X4)-bearing plasmid p47EC. In conclusion, although a low prevalence (0.65%) of (X) in strains was observed in this study, the horizontal transfer of (X4) among isolates mediated by pandemic plasmids and the mobile element IS raises great concerns. Thus, heightened surveillance and immediate action are imperative to curb this clinically significant resistance gene and preserve the efficacy of tigecycline.
替加环素是治疗多重耐药菌引起的严重感染的最后一道抗菌防线。Tet(X)及其众多编码黄素依赖单加氧酶的变体可以赋予替加环素耐药性，其中（X4）是最常见的变体。本研究旨在调查中国扬州不同来源的 分离株中替加环素耐药基因（X）的流行情况，并分析该基因在本地区的传播情况。2022 年，我们检测了来自中国扬州的 618 株不同来源（包括患者、猪相关样本、鸡相关样本和蔬菜）分离株中（X）的存在情况。采用琼脂稀释法或肉汤微量稀释法检测（X）阳性 分离株的抗菌药物敏感性。对（X）阳性株进行全基因组测序，采用 Illumina 和 Oxford Nanopore 平台。从猪或猪肉样本中分离的 4 株携带（X4），对多种抗菌药物（包括替加环素）耐药，分别鉴定为 ST542、ST10、ST761 和 ST48。（X4）基因位于 IncFIA8-IncHI1/ST17（n=2）、IncFIA18-IncFIB(K)-IncX1（n=1）和 IncX1（n=1）质粒上。这些携带（X4）的质粒与中国不同来源具有相同不相容类型的其他携带（X4）的质粒高度相似。它们共享与 IS 相关的（X4）的遗传环境，与首次鉴定的携带（X4）的质粒 p47EC 观察到的情况相同。总之，尽管本研究中 菌株中（X）的检出率较低（0.65%），但携带（X4）的质粒通过流行质粒和移动元件 IS 在 分离株之间的水平转移引起了极大的关注。因此，加强监测和立即采取行动对于遏制这种具有临床重要意义的耐药基因并保持替加环素的疗效至关重要。
