Feng Yiming, Li Tiantian, Zhao Shiyun, Li Xuexue, Zhai Yajun, Yuan Li, Liu Jianhua, Hu Gongzheng, He Dandan, Pan Yushan
College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, PR China.
College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, PR China; Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou, Henan Province, PR China; Henan Province Key Laboratory of Animal Food Pathogens Surveillance, PR China.
Poult Sci. 2025 Mar 24;104(6):105079. doi: 10.1016/j.psj.2025.105079.
The emergence and spread of the multidrug-resistant gene cfr have raised significant public health concerns worldwide. To investigate its prevalence and dissemination dynamics, 18 cfr-positive strains were isolated in 2021 from fecal and environmental samples. Antimicrobial susceptibility testing showed that all strains were 100 % multidrug-resistant. Conjugation experiments demonstrated that a cfr- carrying IncFII(K)-IncR-IncFIB multi-replicon plasmid could transfer to E. coli J53. S1-nuclease digestion and Southern blotting identified cfr on plasmids of varying sizes, while whole-genome sequencing confirmed its presence on multiple plasmid types: IncX4, IncN, IncFII(K)-IncR-IncFIB, IncFIB-IncFII-IncR-IncHI2-IncHI2A multi-replicon plasmids, and two plasmids of unknown types. Genetic environment analysis revealed that cfr is categorized into five distinct structures (Types I-V). Reverse PCR results showed that Types I, II, and IV can form three circular intermediates of varying lengths (cfr-IS26). Network analysis further indicated strong association between cfr, tet(M), and dfrA14 mediated by IS26. Phylogenetic analysis revealed that the four ST1140 E. coli strains and all nine K. pneumoniae strains showed minimal genetic divergence. These findings suggest both clonal and horizontal transmission of cfr within the poultry farm. Continuous monitoring of cfr in animal-related environments is essential to mitigate its potential transfer to humans.
多重耐药基因cfr的出现和传播在全球范围内引发了重大的公共卫生担忧。为调查其流行情况和传播动态，2021年从粪便和环境样本中分离出18株携带cfr的菌株。药敏试验表明，所有菌株均表现为100%多重耐药。接合实验证明，携带cfr的IncFII(K)-IncR-IncFIB多复制子质粒可转移至大肠杆菌J53。S1核酸酶消化和Southern印迹法鉴定出不同大小质粒上的cfr，而全基因组测序证实其存在于多种质粒类型上：IncX4、IncN、IncFII(K)-IncR-IncFIB、IncFIB-IncFII-IncR-IncHI2-IncHI2A多复制子质粒，以及两种未知类型的质粒。遗传环境分析表明，cfr可分为五种不同结构（I型至V型）。反向PCR结果显示，I型、II型和IV型可形成三种不同长度的环状中间体（cfr-IS26）。网络分析进一步表明，cfr、tet(M)和dfrA14之间存在由IS26介导的强关联。系统发育分析表明，四株ST1140大肠杆菌菌株和所有九株肺炎克雷伯菌菌株的遗传差异极小。这些发现表明，cfr在家禽养殖场内存在克隆传播和水平传播。持续监测与动物相关环境中的cfr对于减轻其向人类的潜在转移至关重要。
