Cornell University, Department of Food Science, Ithaca, New York, USA.
J Clin Microbiol. 2013 Jun;51(6):1786-97. doi: 10.1128/JCM.03201-12. Epub 2013 Apr 3.
As the development of molecular serotyping approaches is critical for Salmonella spp., which include >2,600 serovars, we performed an initial evaluation of the ability to identify Salmonella serovars using (i) different molecular subtyping methods and (ii) a newly implemented combined PCR- and sequencing-based approach that directly targets O- and H-antigen-encoding genes. Initial testing was performed using 46 isolates that represent the top 40 Salmonella serovars isolated from human and nonhuman sources, as reported by the U.S. Centers for Disease Control and Prevention and the World Health Organization. Multilocus sequence typing (MLST) was able to accurately predict the serovars for 42/46 isolates and showed the best ability to predict serovars among the subtyping methods tested. Pulsed-field gel electrophoresis (PFGE), ribotyping, and repetitive extragenic palindromic sequence-based PCR (rep-PCR) were able to accurately predict the serovars for 35/46, 34/46, and 30/46 isolates, respectively. Among the methods, S. enterica subsp. enterica serovars 4,5,12:i:-, Typhimurium, and Typhimurium var. 5- were frequently not classified correctly, which is consistent with their close phylogenetic relationship. To develop a PCR- and sequence-based serotyping approach, we integrated available data sources to implement a combination PCR-based O-antigen screening and sequencing of internal fliC and fljB fragments. This approach correctly identified the serovars for 42/46 isolates in the initial set representing the most common Salmonella serovars, as well as for 54/63 isolates representing less common Salmonella serovars. Our study not only indicates that different molecular approaches show the potential to allow for rapid serovar classification of Salmonella isolates, but it also provides data that can help with the selection of molecular serotyping methods to be used by different laboratories.
由于沙门氏菌（包括>2600 个血清型）的分子血清型分析方法的发展至关重要，因此我们（i）使用不同的分子亚型分析方法和（ii）新实施的直接针对 O 抗原和 H 抗原编码基因的组合 PCR 和测序方法，对鉴定沙门氏菌血清型的能力进行了初步评估。初步测试使用了 46 株代表美国疾病控制与预防中心和世界卫生组织报告的从人和非人类来源分离的前 40 种沙门氏菌血清型的分离株。多位点序列分型（MLST）能够准确预测 46 株分离株中的 42 株血清型，并且在测试的亚型分析方法中显示出预测血清型的最佳能力。脉冲场凝胶电泳（PFGE）、核糖体分型和重复外回文序列基序 PCR（rep-PCR）能够分别准确预测 46 株分离株中的 35 株、34 株和 30 株血清型。在这些方法中，S. enterica subsp. enterica 血清型 4、5、12:i:-、肠炎沙门氏菌和肠炎沙门氏菌 var. 5-经常无法正确分类，这与它们密切的系统发育关系一致。为了开发基于 PCR 和序列的血清分型方法，我们整合了可用的数据源，实施了一种基于组合 PCR 的 O 抗原筛选和内部 fliC 和 fljB 片段测序。该方法正确识别了最初代表最常见沙门氏菌血清型的 46 株分离株中的 42 株血清型，以及代表较少见沙门氏菌血清型的 63 株分离株中的 54 株血清型。我们的研究不仅表明，不同的分子方法具有快速鉴定沙门氏菌分离株血清型的潜力，而且还提供了有助于选择不同实验室使用的分子血清型方法的数据。
