Characterization of a genomic island in Stenotrophomonas maltophilia that carries a novel floR gene variant
Characterization of a genomic island in Stenotrophomonas maltophilia that carries a novel floR gene variant
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嗜麦芽寡养单胞菌中携带新型 floR 基因变体的基因组岛的表征
DOI：
10.1093/jac/dku491
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发表时间：
2015-04-01
影响因子：
5.2
通讯作者：
Wang, Yang
中科院分区：
文献类型：
--
作者：
He, Tao;Shen, Jianzhong;Wang, Yang
目的：目的：研究猪源嗜麦芽寡养单胞菌（Stenotrophomonasmaltophilia，S. maltophilia）染色体编码的新的floR基因变异体floRv的结构特征，阐明floRv侧翼区的基因序列和组成。嗜麦芽窄食单胞菌菌株GZP-Sm 1。结果：GZP-Sm 1携带一个floR基因变异体，命名为floRv。E.携带该基因的大肠杆菌克隆对氯霉素和氟苯尼考具有抗性。推导的FloRv蛋白由404个氨基酸组成，与多种FloR蛋白的氨基酸同源性为84.1%~ 91.8%。基因floRv定位于40226 bp GI区域内的MDR区域。在该MDR区域内定位了6个耐药基因，包括floRv（对苯酚的耐药）、tetR-tetA（A）（对四环素的耐药）、strA/strB（对链霉素的耐药）、sul 1（对磺胺类药物的耐药）和aadA 2（对链霉素/大观霉素的耐药）。PCR分析表明，GI不稳定，可以作为环状中间体从染色体上切除。嗜麦芽窄食单胞菌包括floRv在内的6个抗性基因被定位在一个新的GI中。作为动物和人类的机会致病菌，S.嗜麦芽窄食单胞菌可能在农场环境中充当抗性基因库。应监测其对其他病原体的抗性基因传播的贡献。
Objectives: To characterize the chromosomally encoded novel floR gene variant floRv from Stenotrophomonas maltophilia of porcine origin and elucidate the gene order and content of the floRv-flanking regions in an MDR genomic island (GI).Methods: Whole genome sequencing was used to identify the unknown florfenicol resistance gene in S. maltophilia strain GZP-Sm1. The candidate gene was cloned into pMD19-T and Escherichia coli transformants carrying this vector were tested for phenicol MICs. Flanking sequences of the florfenicol resistance gene were identified by a de novo assembly and a primer walking strategy.Results: GZP-Sm1 carried a floR gene variant, designated floRv. E. coli clones carrying this gene were resistant to chloramphenicol and florfenicol. The deduced 404 amino acid FloRv protein showed 84.1%-91.8% amino acid identity to various FloR proteins. The gene floRv was located in an MDR region within a 40226 bp GI region. Six resistance genes, including floRv (phenicol resistance), tetR-tetA(A) (tetracycline resistance), strA/strB (streptomycin resistance), sul1 (sulphonamide resistance) and aadA2 (streptomycin/spectinomycin resistance), were located in this MDR region. PCR analysis revealed that the GI was not stable and could be excised from the chromosome as a circular intermediate.Conclusions: The floRv gene was identified in a porcine S. maltophilia isolate. Six resistance genes including floRv were located in a novel GI. As an opportunistic pathogen in animals and humans, S. maltophilia might act as a resistance gene reservoir in farm environments. Its contribution to the spread of resistance genes to other pathogens should be monitored.