Xia Jing, Sun Jian, Cheng Ke, Li Liang, Fang Liang-Xing, Zou Meng-Ting, Liao Xiao-Ping, Liu Ya-Hong
National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, PR China; College of Veterinary Medicine, South China Agricultural University, Guangzhou, PR China.
National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, PR China; College of Veterinary Medicine, South China Agricultural University, Guangzhou, PR China; Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, PR China.
Vet Microbiol. 2016 May 30;188:41-6. doi: 10.1016/j.vetmic.2016.03.018. Epub 2016 Apr 6.
A total of 963 non-duplicate Escherichia coli strains isolated from food-producing animals between 2002 and 2012 were screened for the presence of the 16S rRNA methyltransferase genes. Among the positive isolates, resistance determinants to extended spectrum β-lactamases, plasmid-mediated quinolone resistance genes as well as floR and fosA/A3/C2 were detected using PCR analysis. These isolates were further subjected to antimicrobial susceptibility testing, molecular typing, PCR-based plasmid replicon typing and plasmid analysis. Of the 963 E. coli isolates, 173 (18.0%), 3 (0.3%) and 2 (0.2%) were rmtB-, armA- and rmtE-positive strains, respectively. All the 16S rRNA methyltransferase gene-positive isolates were multidrug resistant and over 90% of them carried one or more type of resistance gene. IncF (especially IncFII) and non-typeable plasmids played the main role in the dissemination of rmtB, followed by the IncN plasmids. Plasmids that harbored rmtB ranged in size from 20kb to 340kb EcoRI-RFLP testing of the 109 rmtB-positive plasmids from different years and different origins suggested that horizontal (among diverse animals) and vertical transfer of IncF, non-typeable and IncN-type plasmids were responsible for the spread of rmtB gene. In summary, our findings highlight that rmtB was the most prevalent 16S rRNA methyltransferase gene, which present persistent spread in food-producing animals in China and a diverse group of plasmids was responsible for rmtB dissemination.
对2002年至2012年间从产食动物中分离出的963株非重复大肠杆菌菌株进行筛选，以检测16S rRNA甲基转移酶基因的存在情况。在阳性分离株中，使用PCR分析检测了超广谱β-内酰胺酶的耐药决定子、质粒介导的喹诺酮耐药基因以及floR和fosA/A3/C2。这些分离株进一步进行了药敏试验、分子分型、基于PCR的质粒复制子分型和质粒分析。在963株大肠杆菌分离株中，分别有173株（18.0%）、3株（0.3%）和2株（0.2%）为rmtB、armA和rmtE阳性菌株。所有16S rRNA甲基转移酶基因阳性分离株均对多种药物耐药，其中超过90%携带一种或多种耐药基因。IncF（尤其是IncFII）和不可分型质粒在rmtB的传播中起主要作用，其次是IncN质粒。携带rmtB的质粒大小在20kb至340kb之间。对来自不同年份和不同来源的109个rmtB阳性质粒进行EcoRI-RFLP检测表明，IncF、不可分型和IncN型质粒的水平（在不同动物之间）和垂直转移是rmtB基因传播的原因。总之，我们的研究结果突出表明，rmtB是最普遍的16S rRNA甲基转移酶基因，在中国产食动物中持续传播，多种质粒导致了rmtB的传播。
