Jones C Hal, Tuckman Margareta, Murphy Ellen, Bradford Patricia A
Infectious Diseases Research, Wyeth, Pearl River, NY 10965, USA.
J Bacteriol. 2006 Oct;188(20):7151-64. doi: 10.1128/JB.00705-06.
The presence of the tetracycline resistance determinant tet(M) in human clinical isolates of Escherichia coli is described for the first time in this report. The homologue was >99% identical to the tet(M) genes reported to occur in Lactobacillus plantarum, Neisseria meningitidis, and Streptococcus agalactiae, and 3% of the residues in its deduced amino acid sequence diverge from tet(M) of Staphylococcus aureus. Sequence analysis of the regions immediately flanking the gene revealed that sequences upstream of tet(M) in E. coli have homology to Tn916; however, a complete IS26 insertion element was present immediately upstream of the promoter element. Downstream from the termination codon is an insertion sequence that was homologous to the ISVs1 element reported to occur in a plasmid from Vibrio salmonicida that has been associated with another tetracycline resistance determinant, tet(E). Results of mating experiments demonstrated that the E. coli tet(M) gene was on a mobile element so that resistance to tetracycline and minocycline could be transferred to a susceptible strain by conjugation. Expression of the cloned tet(M) gene, under the control of its own promoter, provided tetracycline and minocycline resistance to the E. coli host.
本报告首次描述了在人源临床大肠杆菌分离株中存在四环素抗性决定簇tet(M)。该同源物与据报道存在于植物乳杆菌、脑膜炎奈瑟菌和无乳链球菌中的tet(M)基因的同一性>99%，其推导氨基酸序列中有3%的残基与金黄色葡萄球菌的tet(M)不同。对该基因紧邻区域的序列分析表明，大肠杆菌中tet(M)上游的序列与Tn916具有同源性；然而，在启动子元件紧邻上游存在一个完整的IS26插入元件。终止密码子下游是一个插入序列，它与据报道存在于鲑鱼弧菌质粒中的ISVs1元件同源，该质粒与另一个四环素抗性决定簇tet(E)有关。接合实验结果表明，大肠杆菌tet(M)基因位于一个可移动元件上，因此对四环素和米诺环素的抗性可通过接合转移至敏感菌株。在其自身启动子的控制下，克隆的tet(M)基因的表达赋予大肠杆菌宿主对四环素和米诺环素的抗性。
