临床分离的嗜麦芽寡养单胞菌中 Smqnr 家族喹诺酮类耐药基因的新型变异体。
Novel variants of the Smqnr family of quinolone resistance genes in clinical isolates of Stenotrophomonas maltophilia.
机构信息
Division of Infection, Barts & The London NHS Trust, Newark Street, Whitechapel, London E1 2ES, UK.
出版信息
J Antimicrob Chemother. 2010 Mar;65(3):483-9. doi: 10.1093/jac/dkp476. Epub 2010 Jan 12.
BACKGROUND
Recent analysis of Stenotrophomonas maltophilia has identified a novel family of resistance genes (Smqnr) encoding pentapeptide repeat proteins, which confer low-level resistance to quinolones. This study describes further novel variants present in clinical isolates of S. maltophilia and investigates their effect on resistance to a number of quinolones in an Escherichia coli host.
METHODS
PCR for Smqnr alleles was carried out on a selection of S. maltophilia from clinical specimens, and amplicons were cloned and transformed in E. coli TOP10 cells. Transformed colonies carrying the plasmid were tested for susceptibility to a range of quinolones by MIC determination. DNA sequences were determined and translated peptide sequences compared with known SmQnr sequences.
RESULTS
Thirteen isolates were found to contain Smqnr alleles, of which six corresponded to previously identified Smqnr sequences, while seven were novel variants. Increases in quinolone MICs compared with wild-type E. coli TOP10 were seen for all strains transformed with Smqnr alleles.
CONCLUSIONS
There is considerable diversity within Smqnr alleles. S. maltophilia may be a significant reservoir for the dissemination of quinolone resistance elements to Enterobacteriaceae.
背景
最近对嗜麦芽寡养单胞菌的分析确定了一个新的耐药基因家族（Smqnr），该家族编码五肽重复蛋白，对喹诺酮类药物具有低水平的耐药性。本研究描述了嗜麦芽寡养单胞菌临床分离株中存在的进一步新型变异体，并研究了它们对大肠杆菌宿主中多种喹诺酮类药物的耐药性的影响。
方法
对来自临床标本的嗜麦芽寡养单胞菌进行 Smqnr 等位基因的 PCR 分析，扩增子被克隆并转化到大肠杆菌 TOP10 细胞中。携带质粒的转化菌落通过 MIC 测定来检测对一系列喹诺酮类药物的敏感性。确定 DNA 序列并将翻译的肽序列与已知的 SmQnr 序列进行比较。
结果
发现 13 株分离株含有 Smqnr 等位基因，其中 6 株与先前鉴定的 Smqnr 序列相对应，而 7 株为新型变异体。与野生型大肠杆菌 TOP10 相比，所有转化 Smqnr 等位基因的菌株的喹诺酮 MIC 均升高。
结论
Smqnr 等位基因存在很大的多样性。嗜麦芽寡养单胞菌可能是肠杆菌科中喹诺酮类耐药元件传播的重要储库。
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