Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan Province, People's Republic of China.
Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, People's Republic of China.
J Antimicrob Chemother. 2019 Mar 1;74(3):603-606. doi: 10.1093/jac/dky494.
To characterize the presence and genetic environment of the multiresistance gene cfr in bacterial isolates from a swine farm.
A total of 97 bacterial isolates, recovered from 32 faecal swabs obtained on one farm, were tested for the presence of the cfr gene by PCR. Species identification of the one cfr-positive strain was conducted using the BD PhoenixTM 100 Automated Microbiology System. Susceptibility testing was carried out by broth microdilution. The genetic environment of the cfr gene was analysed by WGS.
The Morganella morganii isolate BCMM24 was the only cfr-positive strain. The cfr gene, as well as 15 other resistance genes, is located on a novel 111238 bp transposon derived from Tn7, designated as Tn6451, which comprises various genetic materials including a novel class 1 integron with five gene cassettes. The cfr-containing region consists of a novel genetic structure IS26-cfr-ΔTn554 tnpB-ΔTn3 family tnpA-IS26, differing from previous reports. Two-step PCR results show that the structure can be looped out and that Tn6451 cannot be excised from the chromosome.
To the best of our knowledge, we report the cfr gene in M. morganii for the first time. The cfr gene and 15 other resistance genes are located on a novel Tn7 transposon derivative, suggesting that the Tn7 transposon may act as a reservoir for various antimicrobial resistance genes and more Tn7 derivatives carrying multiple resistance genes are likely to be discovered in Gram-negative bacteria of both animal and human origin.
分析猪场分离的细菌中多耐药基因 cfr 的存在和遗传环境。
对来自一个猪场的 32 份粪便拭子中分离的 97 株细菌进行 PCR 检测以确定 cfr 基因的存在。采用 BD PhoenixTM 100 自动化微生物系统对 1 株 cfr 阳性菌株进行种属鉴定。采用肉汤微量稀释法进行药敏试验。采用 WGS 分析 cfr 基因的遗传环境。
Morganella morganii 分离株 BCMM24 是唯一一株 cfr 阳性菌。cfr 基因和 15 个其他耐药基因位于一个新型的 111238 bp 转座子上，该转座子来源于 Tn7，被命名为 Tn6451，它包含各种遗传物质，包括一个新型的带有五个基因盒的 class 1 整合子。cfr 基因的基因结构为 IS26-cfr-ΔTn554 tnpB-ΔTn3 家族 tnpA-IS26，与之前的报道不同。两步 PCR 结果表明，该结构可被环出，且 Tn6451 不能从染色体上切除。
据我们所知，这是首次在 M. morganii 中发现 cfr 基因。cfr 基因和 15 个其他耐药基因位于一个新型的 Tn7 转座子衍生物上，这表明 Tn7 转座子可能是各种抗生素耐药基因的储存库，并且在动物和人类来源的革兰氏阴性菌中可能会发现更多带有多种耐药基因的 Tn7 衍生物。
