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首页> 美国卫生研究院文献>Journal of Clinical Microbiology >Clonal Expansion and Microevolution of Quinolone-Resistant Salmonella enterica Serotype Typhi in Vietnam from 1996 to 2004
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Clonal Expansion and Microevolution of Quinolone-Resistant Salmonella enterica Serotype Typhi in Vietnam from 1996 to 2004

机译：1996年至2004年越南耐喹诺酮小肠沙门氏菌血清型鼠伤寒沙门氏菌的克隆扩增和微进化

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Salmonella enterica serotype Typhi clinical isolates (n = 91) resistant to nalidixic acid (Nalr) were collected from sporadic cases and minor outbreaks throughout Vietnam between 1996 and 2004. These isolates were typed and compared by four methods: Vi phage typing, PstI ribotyping, XbaI and SpeI pulsed-field gel electrophoresis (PFGE), and single-nucleotide polymorphism (SNP) analysis. The results indicated that 65% of the isolates were not typeable by Vi phage typing. In contrast, the ribotyping and, with more accuracy, the SNP analysis methods indicated that all Nalr isolates belonged to a single clone (ribotype 3a, haplotype H58) that was found previously and that largely consisted of plasmid-encoded multidrug-resistant serotype Typhi isolates. PFGE demonstrated the occurrence of microevolution within this clone. We identified two major combined PFGE profiles: X1-S1 and X3-S6. X3-S6 predominated between 1996 and 2002 but was replaced by X1-S1 after 2002. Nevertheless, PFGE, with a Simpson's index of 0.78, was not considered an optimal discriminatory method for investigating typhoid fever outbreaks in Vietnam. The rate of quinolone resistance increased and the rate of multidrug resistance decreased during the study period. From 2002 to 2004, 80.6% of the isolates from South Vietnam were resistant only to Nal. The mechanism of Nal resistance in most of the isolates (94%) was a mutation in the quinolone resistance-determining chromosomal region of gyrA that led to the amino acid substitution Ser83Phe. No plasmid-located qnrA, qnrB, or qnrS was detected.
机译：在1996年至2004年间从越南各地的零星病例和小规模暴发中收集到了耐萘啶酸（Nal r ）的肠炎沙门氏菌血清型Typhi临床分离株（n = 91）。对这些分离株进行了分类和四种方法的比较：噬菌体分型，PstI核糖分型，XbaI和SpeI脉冲场凝胶电泳（PFGE）和单核苷酸多态性（SNP）分析。结果表明65％的分离物不能通过噬菌体分型。相比之下，核糖分型和更精确的SNP分析方法表明，所有Nal r 分离株均属于单个克隆（核糖型3a，单倍型H58），该克隆先前已发现并且主要由质粒组成编码的多重耐药血清型鼠疫分离物。 PFGE证明了该克隆中发生了微进化。我们确定了两个主要的PFGE组合曲线：X1-S1和X3-S6。 X3-S6在1996年至2002年期间占主导地位，但在2002年之后被X1-S1所取代。尽管如此，PFGE的辛普森指数为0.78，不被认为是调查越南伤寒疫情的最佳判别方法。在研究期间，喹诺酮耐药率增加而多药耐药率下降。从2002年到2004年，来自南越的分离株中80.6％仅对Nal具有抗性。大多数分离株（94％）中，Nal耐药的机制是决定了gyrA喹诺酮耐药性的染色体区域发生突变，该突变导致氨基酸取代Ser83Phe。没有检测到位于质粒的qnrA，qnrB或qnrS。

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