Li Yingshan, Peng Kai, Yin Yi, Sun Xinran, Zhang Wenhui, Li Ruichao, Wang Zhiqiang
College of Veterinary Medicine, Yangzhou University, Yangzhou, China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
Front Microbiol. 2021 Dec 20;12:751006. doi: 10.3389/fmicb.2021.751006. eCollection 2021.
Many novel tigecycline-inactivating enzymes encoded by (X) variants from different bacteria were discovered since the plasmid-mediated (X3) and (X4) genes conferring high-level resistance to tigecycline in Enterobacterales and were reported. However, there have been no comprehensive studies of the prevalence of different (X) variants in poultry farms. In this study, we collected 45 chicken fecal samples, isolated (X)-positive strains, and performed antimicrobial susceptibility testing, conjugation assay, whole-genome sequencing, and bioinformatics analysis. A total of 15 (X)-bearing strains were isolated from 13 samples. Species identification and (X) subtyping analysis found that the 15 strains belonged to eight different species and harbored four different (X) variants. Genomic investigation showed that transmission of (X) variants was associated with various mobile genetic elements, and (X4) was the most prevalent variant transferred by conjugative plasmids. Meanwhile, we characterized a plasmid co-harboring (X6) and in . In summary, we demonstrated that different (X) variants were widely disseminated in the chicken farming environment and dominated by (X4). This finding expands the understanding of the prevalence of (X) among different animal sources, and it was advocated to reduce the usage of antibiotics to limit the emergence and transmission of novel (X) variants in the poultry industry.
自从报道了在肠杆菌科细菌中赋予对替加环素高水平耐药性的质粒介导的（X3）和（X4）基因以来，已发现许多由不同细菌的（X）变体编码的新型替加环素失活酶。然而，尚未对家禽养殖场中不同（X）变体的流行情况进行全面研究。在本研究中，我们收集了45份鸡粪便样本，分离出（X）阳性菌株，并进行了药敏试验、接合试验、全基因组测序和生物信息学分析。从13个样本中总共分离出15株携带（X）的菌株。物种鉴定和（X）亚型分析发现，这15株菌株属于8个不同的物种，并携带4种不同的（X）变体。基因组研究表明，（X）变体的传播与各种移动遗传元件有关，并且（X4）是通过接合质粒转移的最普遍的变体。同时，我们鉴定了一株在[具体菌种]中共携带（X6）和[另一种基因]的质粒。总之，我们证明了不同的（X）变体在家养鸡养殖环境中广泛传播，且以（X4）为主。这一发现扩展了对（X）在不同动物来源中流行情况的认识，并提倡减少抗生素的使用以限制家禽业中新型（X）变体的出现和传播。
